diff --git a/src/main/java/org/codelibs/fess/Constants.java b/src/main/java/org/codelibs/fess/Constants.java
index 5cf7aeb95..dbe15cef3 100644
--- a/src/main/java/org/codelibs/fess/Constants.java
+++ b/src/main/java/org/codelibs/fess/Constants.java
@@ -184,7 +184,8 @@ public class Constants extends CoreLibConstants {
             + ",YandexBot"//
             + ",Chilkat"//
             + ",CloudFront"//
-            + ",Mediapartners";
+            + ",Mediapartners"//
+            + ",MSIE 6";
 
     public static final String DEFAULT_FROM_EMAIL = "Administrator <root@localhost>";
 
diff --git a/src/main/java/org/codelibs/fess/api/es/EsApiManager.java b/src/main/java/org/codelibs/fess/api/es/EsApiManager.java
index f503fb48f..40c9831cc 100644
--- a/src/main/java/org/codelibs/fess/api/es/EsApiManager.java
+++ b/src/main/java/org/codelibs/fess/api/es/EsApiManager.java
@@ -107,7 +107,7 @@ public class EsApiManager extends BaseApiManager {
             }
         }
 
-        if (path.startsWith("/_plugin/") || path.equals("/_plugin")) {
+        if (path.equals("/_plugin") || path.startsWith("/_plugin/")) {
             processPluginRequest(request, response, path.replaceFirst("^/_plugin", StringUtil.EMPTY));
             return;
         }
@@ -154,7 +154,7 @@ public class EsApiManager extends BaseApiManager {
         });
     }
 
-    private void processPluginRequest(final HttpServletRequest request, final HttpServletResponse response, final String path) {
+    protected void processPluginRequest(final HttpServletRequest request, final HttpServletResponse response, final String path) {
         Path filePath = ResourceUtil.getSitePath(path.replaceAll("\\.\\.+", StringUtil.EMPTY).replaceAll("/+", "/").split("/"));
         if (Files.isDirectory(filePath)) {
             filePath = filePath.resolve("index.html");
diff --git a/src/main/java/org/codelibs/fess/api/gsa/GsaApiManager.java b/src/main/java/org/codelibs/fess/api/gsa/GsaApiManager.java
index 3f5bf86e8..2b2abd3aa 100644
--- a/src/main/java/org/codelibs/fess/api/gsa/GsaApiManager.java
+++ b/src/main/java/org/codelibs/fess/api/gsa/GsaApiManager.java
@@ -59,9 +59,9 @@ import org.slf4j.LoggerFactory;
 public class GsaApiManager extends BaseApiManager implements WebApiManager {
     private static final Logger logger = LoggerFactory.getLogger(GsaApiManager.class);
 
-    public String gsaPathPrefix = "/gsa";
+    protected String gsaPathPrefix = "/gsa";
 
-    public String gsaMetaPrefix = "MT_";
+    protected String gsaMetaPrefix = "MT_";
 
     private static final String GSA_META_SUFFIX = "_s";
 
@@ -284,9 +284,6 @@ public class GsaApiManager extends BaseApiManager implements WebApiManager {
         buf.append("<GSP VER=\"");
         buf.append(Constants.GSA_API_VERSION);
         buf.append("\">");
-        //        buf.append("<status>");
-        //        buf.append(status);
-        //        buf.append("</status>");
         if (status == 0) {
             buf.append(body);
         } else {
@@ -394,24 +391,6 @@ public class GsaApiManager extends BaseApiManager implements WebApiManager {
 
         @Override
         public String[] getExtraQueries() {
-            /*
-            List<String> additional = new ArrayList<String>();
-            // collections
-            final String site = (String) request.getParameter("site");
-            if (StringUtil.isNotBlank(site)) {
-                additional.add(" (label:" + site.replace(".", " AND label:").replace("|", " OR label:") + ")");
-            }
-            // dynmic fields
-            final String requiredFields = (String) request.getParameter("requiredfields");
-            if (StringUtil.isNotBlank(requiredFields)) {
-                additional.add(" (" + gsaMetaPrefix
-                        + requiredFields.replace(":", "_s:").replace(".", " AND " + gsaMetaPrefix).replace("|", " OR " + gsaMetaPrefix)
-                        + ")");
-            }
-            if (!additional.isEmpty()) {
-                extraParams.put("additional", (String[]) additional.toArray(new String[additional.size()]));
-            }
-            */
             return getParamValueArray(request, "ex_q");
         }
 
@@ -445,28 +424,6 @@ public class GsaApiManager extends BaseApiManager implements WebApiManager {
 
         @Override
         public String getSort() {
-            /*
-            // sorting
-            final String sort = request.getParameter("sort");
-            if (StringUtil.isNotBlank(sort)) {
-                final String[] sortParams = sort.split(":");
-                String sortDirection = "desc";
-                if ("date".equals(sortParams[0])) {
-                    if ("A".equals(sortParams[1])) {
-                        sortDirection = "asc";
-                    } else if ("D".equals(sortParams[1])) {
-                        sortDirection = "desc";
-                    }
-                    // TODO: Now ignore sort mode
-                    //                    if ("S".equals(sortParams[2])) {
-                    //                    } else if ("R".equals(sortParams[2])) {
-                    //                    } else if ("L".equals(sortParams[2])) {
-                    //                    }
-                    // sortParams[3]=<mode> is fixed as "d1"
-                    extraParams.put("sort", new String[] { "lastModified." + sortDirection });
-                }
-            }
-            */
             return request.getParameter("sort");
         }
 
@@ -532,4 +489,12 @@ public class GsaApiManager extends BaseApiManager implements WebApiManager {
         }
 
     }
+
+    public void setGsaPathPrefix(final String gsaPathPrefix) {
+        this.gsaPathPrefix = gsaPathPrefix;
+    }
+
+    public void setGsaMetaPrefix(final String gsaMetaPrefix) {
+        this.gsaMetaPrefix = gsaMetaPrefix;
+    }
 }
diff --git a/src/main/java/org/codelibs/fess/api/json/JsonApiManager.java b/src/main/java/org/codelibs/fess/api/json/JsonApiManager.java
index 01194699d..22fd3bae0 100644
--- a/src/main/java/org/codelibs/fess/api/json/JsonApiManager.java
+++ b/src/main/java/org/codelibs/fess/api/json/JsonApiManager.java
@@ -299,28 +299,29 @@ public class JsonApiManager extends BaseJsonApiManager {
         }
     }
 
-    protected String detailedMessage(Throwable t) {
+    protected String detailedMessage(final Throwable t) {
         if (t == null) {
             return "Unknown";
         }
-        if (t.getCause() != null) {
+        Throwable target = t;
+        if (target.getCause() != null) {
             final StringBuilder sb = new StringBuilder();
-            while (t != null) {
-                sb.append(t.getClass().getSimpleName());
-                if (t.getMessage() != null) {
+            while (target != null) {
+                sb.append(target.getClass().getSimpleName());
+                if (target.getMessage() != null) {
                     sb.append("[");
-                    sb.append(t.getMessage());
+                    sb.append(target.getMessage());
                     sb.append("]");
                 }
                 sb.append("; ");
-                t = t.getCause();
-                if (t != null) {
+                target = target.getCause();
+                if (target != null) {
                     sb.append("nested: ");
                 }
             }
             return sb.toString();
         } else {
-            return t.getClass().getSimpleName() + "[" + t.getMessage() + "]";
+            return target.getClass().getSimpleName() + "[" + target.getMessage() + "]";
         }
     }
 
diff --git a/src/main/java/org/codelibs/fess/app/web/admin/backup/AdminBackupAction.java b/src/main/java/org/codelibs/fess/app/web/admin/backup/AdminBackupAction.java
index 8510f5a67..4698c0f26 100644
--- a/src/main/java/org/codelibs/fess/app/web/admin/backup/AdminBackupAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/admin/backup/AdminBackupAction.java
@@ -328,7 +328,7 @@ public class AdminBackupAction extends FessAdminAction {
     }
 
     static public List<Map<String, String>> getBackupItems() {
-        FessConfig fessConfig = ComponentUtil.getFessConfig();
+        final FessConfig fessConfig = ComponentUtil.getFessConfig();
         return stream(fessConfig.getIndexBackupAllTargets()).get(stream -> stream.map(name -> {
             final Map<String, String> map = new HashMap<>();
             map.put("id", name);
diff --git a/src/main/java/org/codelibs/fess/app/web/admin/upgrade/AdminUpgradeAction.java b/src/main/java/org/codelibs/fess/app/web/admin/upgrade/AdminUpgradeAction.java
index 250d060d3..599d8e18b 100644
--- a/src/main/java/org/codelibs/fess/app/web/admin/upgrade/AdminUpgradeAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/admin/upgrade/AdminUpgradeAction.java
@@ -202,7 +202,7 @@ public class AdminUpgradeAction extends FessAdminAction {
         }
     }
 
-    private boolean startReindex(boolean replaceAliases) {
+    private boolean startReindex(final boolean replaceAliases) {
         final String docIndex = "fess";
         final String fromIndex = fessConfig.getIndexDocumentUpdateIndex();
         final String toIndex = docIndex + "." + new SimpleDateFormat("yyyyMMddHHmm").format(new Date());
diff --git a/src/main/java/org/codelibs/fess/app/web/api/ApiResult.java b/src/main/java/org/codelibs/fess/app/web/api/ApiResult.java
index 56f377c49..b3c07409a 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/ApiResult.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/ApiResult.java
@@ -190,10 +190,10 @@ public class ApiResult {
                 // facet field
                 if (facetResponse.getFieldList() != null) {
                     facetField = facetResponse.getFieldList().stream().map(field -> {
-                        Map<String, Object> fieldMap = new HashMap<>(2, 1f);
+                        final Map<String, Object> fieldMap = new HashMap<>(2, 1f);
                         fieldMap.put("name", field.getName());
                         fieldMap.put("result", field.getValueCountMap().entrySet().stream().map(e -> {
-                            Map<String, Object> valueCount = new HashMap<>(2, 1f);
+                            final Map<String, Object> valueCount = new HashMap<>(2, 1f);
                             valueCount.put("value", e.getKey());
                             valueCount.put("count", e.getValue());
                             return valueCount;
@@ -204,7 +204,7 @@ public class ApiResult {
                 // facet q
                 if (facetResponse.getQueryCountMap() != null) {
                     facetQuery = facetResponse.getQueryCountMap().entrySet().stream().map(e -> {
-                        Map<String, Object> valueCount = new HashMap<>(2, 1f);
+                        final Map<String, Object> valueCount = new HashMap<>(2, 1f);
                         valueCount.put("value", e.getKey());
                         valueCount.put("count", e.getValue());
                         return valueCount;
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/backup/ApiAdminBackupAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/backup/ApiAdminBackupAction.java
index 0a239b6ac..28a71a3e8 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/backup/ApiAdminBackupAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/backup/ApiAdminBackupAction.java
@@ -63,7 +63,7 @@ public class ApiAdminBackupAction extends FessApiAdminAction {
     // GET /api/admin/backup/file/{id}
     @Execute
     public StreamResponse get$file(final String id) {
-        FessConfig fessConfig = ComponentUtil.getFessConfig();
+        final FessConfig fessConfig = ComponentUtil.getFessConfig();
         if (stream(fessConfig.getIndexBackupAllTargets()).get(stream -> stream.anyMatch(s -> s.equals(id)))) {
             if (id.equals("system.properties")) {
                 return asStream(id).contentTypeOctetStream().stream(out -> {
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/kuromoji/ApiAdminDictKuromojiAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/kuromoji/ApiAdminDictKuromojiAction.java
index 81a1eba7f..80e209bc7 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/kuromoji/ApiAdminDictKuromojiAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/kuromoji/ApiAdminDictKuromojiAction.java
@@ -18,6 +18,7 @@ package org.codelibs.fess.app.web.api.admin.dict.kuromoji;
 import static org.codelibs.fess.app.web.admin.dict.kuromoji.AdminDictKuromojiAction.createKuromojiItem;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
 import java.util.stream.Collectors;
 
@@ -116,8 +117,7 @@ public class ApiAdminDictKuromojiAction extends FessApiAdminAction {
         });
         try (InputStream inputStream = form.kuromojiFile.getInputStream()) {
             file.update(inputStream);
-        } catch (final Throwable e) {
-            e.printStackTrace();
+        } catch (final IOException e) {
             throwValidationErrorApi(messages -> messages.addErrorsFailedToUploadProtwordsFile(GLOBAL));
         }
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/mapping/ApiAdminDictMappingAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/mapping/ApiAdminDictMappingAction.java
index 626c8327c..3b79ae7e3 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/mapping/ApiAdminDictMappingAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/mapping/ApiAdminDictMappingAction.java
@@ -16,6 +16,7 @@
 package org.codelibs.fess.app.web.api.admin.dict.mapping;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
 import java.util.stream.Collectors;
 
@@ -121,8 +122,7 @@ public class ApiAdminDictMappingAction extends FessApiAdminAction {
         });
         try (InputStream inputStream = form.charMappingFile.getInputStream()) {
             file.update(inputStream);
-        } catch (final Throwable e) {
-            e.printStackTrace();
+        } catch (final IOException e) {
             throwValidationErrorApi(messages -> messages.addErrorsFailedToUploadProtwordsFile(GLOBAL));
         }
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/protwords/ApiAdminDictProtwordsAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/protwords/ApiAdminDictProtwordsAction.java
index 958e4cba6..d3823fe94 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/protwords/ApiAdminDictProtwordsAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/protwords/ApiAdminDictProtwordsAction.java
@@ -18,6 +18,7 @@ package org.codelibs.fess.app.web.api.admin.dict.protwords;
 import static org.codelibs.fess.app.web.admin.dict.protwords.AdminDictProtwordsAction.createProtwordsItem;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
 import java.util.stream.Collectors;
 
@@ -121,8 +122,7 @@ public class ApiAdminDictProtwordsAction extends FessApiAdminAction {
         });
         try (InputStream inputStream = form.protwordsFile.getInputStream()) {
             file.update(inputStream);
-        } catch (final Throwable e) {
-            e.printStackTrace();
+        } catch (final IOException e) {
             throwValidationErrorApi(messages -> messages.addErrorsFailedToUploadProtwordsFile(GLOBAL));
         }
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/seunjeon/ApiAdminDictSeunjeonAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/seunjeon/ApiAdminDictSeunjeonAction.java
index 0f50bf33b..5fadba00d 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/seunjeon/ApiAdminDictSeunjeonAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/seunjeon/ApiAdminDictSeunjeonAction.java
@@ -16,6 +16,7 @@
 package org.codelibs.fess.app.web.api.admin.dict.seunjeon;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
 import java.util.stream.Collectors;
 
@@ -121,8 +122,7 @@ public class ApiAdminDictSeunjeonAction extends FessApiAdminAction {
         });
         try (InputStream inputStream = form.seunjeonFile.getInputStream()) {
             file.update(inputStream);
-        } catch (final Throwable e) {
-            e.printStackTrace();
+        } catch (final IOException e) {
             throwValidationErrorApi(messages -> messages.addErrorsFailedToUploadProtwordsFile(GLOBAL));
         }
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/synonym/ApiAdminDictSynonymAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/synonym/ApiAdminDictSynonymAction.java
index 298957be5..4405f3cc6 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/dict/synonym/ApiAdminDictSynonymAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/dict/synonym/ApiAdminDictSynonymAction.java
@@ -16,6 +16,7 @@
 package org.codelibs.fess.app.web.api.admin.dict.synonym;
 
 import java.io.File;
+import java.io.IOException;
 import java.io.InputStream;
 import java.util.stream.Collectors;
 
@@ -121,8 +122,7 @@ public class ApiAdminDictSynonymAction extends FessApiAdminAction {
         });
         try (InputStream inputStream = form.synonymFile.getInputStream()) {
             file.update(inputStream);
-        } catch (final Throwable e) {
-            e.printStackTrace();
+        } catch (final IOException e) {
             throwValidationErrorApi(messages -> messages.addErrorsFailedToUploadProtwordsFile(GLOBAL));
         }
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
diff --git a/src/main/java/org/codelibs/fess/app/web/base/FessSearchAction.java b/src/main/java/org/codelibs/fess/app/web/base/FessSearchAction.java
index 2c93e6082..aedb5bbee 100644
--- a/src/main/java/org/codelibs/fess/app/web/base/FessSearchAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/base/FessSearchAction.java
@@ -222,7 +222,7 @@ public abstract class FessSearchAction extends FessBaseAction {
         return newHtmlResponseAsRediect(StringUtil.isBlank(contextPath) ? "/" : contextPath);
     }
 
-    protected HtmlNext virtualHost(HtmlNext path) {
+    protected HtmlNext virtualHost(final HtmlNext path) {
         return fessConfig.getVirtualHostPath(path);
     }
 }
diff --git a/src/main/java/org/codelibs/fess/crawler/FessCrawlerThread.java b/src/main/java/org/codelibs/fess/crawler/FessCrawlerThread.java
index 17caaacf9..065442213 100644
--- a/src/main/java/org/codelibs/fess/crawler/FessCrawlerThread.java
+++ b/src/main/java/org/codelibs/fess/crawler/FessCrawlerThread.java
@@ -253,9 +253,9 @@ public class FessCrawlerThread extends CrawlerThread {
     protected void processResponse(final UrlQueue<?> urlQueue, final ResponseData responseData) {
         super.processResponse(urlQueue, responseData);
 
-        FessConfig fessConfig = ComponentUtil.getFessConfig();
+        final FessConfig fessConfig = ComponentUtil.getFessConfig();
         if (fessConfig.isCrawlerFailureUrlStatusCodes(responseData.getHttpStatusCode())) {
-            String sessionId = crawlerContext.getSessionId();
+            final String sessionId = crawlerContext.getSessionId();
             final CrawlingConfig crawlingConfig = ComponentUtil.getCrawlingConfigHelper().get(sessionId);
             final String url = urlQueue.getUrl();
 
diff --git a/src/main/java/org/codelibs/fess/crawler/transformer/FessXpathTransformer.java b/src/main/java/org/codelibs/fess/crawler/transformer/FessXpathTransformer.java
index 18b042259..12ed3fe82 100644
--- a/src/main/java/org/codelibs/fess/crawler/transformer/FessXpathTransformer.java
+++ b/src/main/java/org/codelibs/fess/crawler/transformer/FessXpathTransformer.java
@@ -727,7 +727,7 @@ public class FessXpathTransformer extends XpathTransformer implements FessTransf
                                 }
                             }
                         }
-                    } catch (Exception e) {
+                    } catch (final Exception e) {
                         logger.debug("Failed to parse " + imgNode + " at " + responseData.getUrl(), e);
                     }
                 } else if (firstSrcNode == null) {
@@ -744,7 +744,7 @@ public class FessXpathTransformer extends XpathTransformer implements FessTransf
                     if (thumbnailUrl != null) {
                         return thumbnailUrl.toExternalForm();
                     }
-                } catch (Exception e) {
+                } catch (final Exception e) {
                     logger.debug("Failed to parse " + firstSrcNode + " at " + responseData.getUrl(), e);
                 }
             }
@@ -755,7 +755,7 @@ public class FessXpathTransformer extends XpathTransformer implements FessTransf
     }
 
     protected Integer getAttributeAsInteger(final NamedNodeMap attributes, final String name) {
-        Node namedItem = attributes.getNamedItem(name);
+        final Node namedItem = attributes.getNamedItem(name);
         if (namedItem == null) {
             return null;
         }
diff --git a/src/main/java/org/codelibs/fess/ds/impl/GitBucketDataStoreImpl.java b/src/main/java/org/codelibs/fess/ds/impl/GitBucketDataStoreImpl.java
index f9e8f4229..098a6b892 100644
--- a/src/main/java/org/codelibs/fess/ds/impl/GitBucketDataStoreImpl.java
+++ b/src/main/java/org/codelibs/fess/ds/impl/GitBucketDataStoreImpl.java
@@ -180,7 +180,7 @@ public class GitBucketDataStoreImpl extends AbstractDataStoreImpl {
             @SuppressWarnings({ "rawtypes", "unchecked" })
             final Map<String, String> map = (Map) curlResponse.getContentAsMap();
             assert (map.containsKey("version"));
-            assert (map.containsKey("source_label") && map.containsKey("wiki_label") & map.containsKey("issue_label"));
+            assert (map.containsKey("source_label") && map.containsKey("wiki_label") && map.containsKey("issue_label"));
             return map;
 
         } catch (final Exception e) {
@@ -205,12 +205,13 @@ public class GitBucketDataStoreImpl extends AbstractDataStoreImpl {
                 assert (map.containsKey("repositories"));
 
                 totalCount = (int) map.get("total_count");
-                int responseCount = (int) map.get("response_count");
-                if (responseCount == 0)
+                final int responseCount = (int) map.get("response_count");
+                if (responseCount == 0) {
                     break;
+                }
 
                 @SuppressWarnings("unchecked")
-                List<Map<String, Object>> repos = (ArrayList<Map<String, Object>>) map.get("repositories");
+                final List<Map<String, Object>> repos = (ArrayList<Map<String, Object>>) map.get("repositories");
                 repoList.addAll(repos);
             } catch (final Exception e) {
                 logger.warn("Failed to access to " + urlWithOffset, e);
@@ -332,14 +333,15 @@ public class GitBucketDataStoreImpl extends AbstractDataStoreImpl {
 
     private List<String> getIssueComments(final String issueUrl, final String authToken) {
         final String commentsUrl = issueUrl + "/comments";
-        final List<String> commentList = new ArrayList<String>();
+        final List<String> commentList = new ArrayList<>();
 
         try (CurlResponse curlResponse = Curl.get(commentsUrl).header("Authorization", "token " + authToken).execute()) {
             final String commentsJson = curlResponse.getContentAsString();
-            List<Map<String, Object>> comments = new ObjectMapper().readValue(commentsJson, new TypeReference<List<Map<String, Object>>>() {
-            });
+            final List<Map<String, Object>> comments =
+                    new ObjectMapper().readValue(commentsJson, new TypeReference<List<Map<String, Object>>>() {
+                    });
 
-            for (Map<String, Object> comment : comments) {
+            for (final Map<String, Object> comment : comments) {
                 if (comment.containsKey("body")) {
                     commentList.add((String) comment.get("body"));
                 }
diff --git a/src/main/java/org/codelibs/fess/es/client/FessEsClient.java b/src/main/java/org/codelibs/fess/es/client/FessEsClient.java
index eb8fdc2eb..0e24c6e6c 100644
--- a/src/main/java/org/codelibs/fess/es/client/FessEsClient.java
+++ b/src/main/java/org/codelibs/fess/es/client/FessEsClient.java
@@ -311,7 +311,7 @@ public class FessEsClient implements Client {
                 } else {
                     indexName = configIndex;
                 }
-                boolean exists = existsIndex(indexName);
+                final boolean exists = existsIndex(indexName);
                 if (!exists) {
                     final String createdIndexName;
                     if (isFessIndex) {
@@ -370,7 +370,7 @@ public class FessEsClient implements Client {
             } else {
                 logger.warn("Failed to reindex from " + fromIndex + " to " + toIndex);
             }
-        } catch (IOException e) {
+        } catch (final IOException e) {
             logger.warn("Failed to reindex from " + fromIndex + " to " + toIndex, e);
         }
         return false;
@@ -442,8 +442,8 @@ public class FessEsClient implements Client {
 
     public boolean updateAlias(final String newIndex) {
         final FessConfig fessConfig = ComponentUtil.getFessConfig();
-        String updateAlias = fessConfig.getIndexDocumentUpdateIndex();
-        String searchAlias = fessConfig.getIndexDocumentSearchIndex();
+        final String updateAlias = fessConfig.getIndexDocumentUpdateIndex();
+        final String searchAlias = fessConfig.getIndexDocumentSearchIndex();
         final GetIndexResponse response1 =
                 client.admin().indices().prepareGetIndex().addIndices(updateAlias).execute().actionGet(fessConfig.getIndexIndicesTimeout());
         final String[] updateIndices = response1.indices();
@@ -451,15 +451,15 @@ public class FessEsClient implements Client {
                 client.admin().indices().prepareGetIndex().addIndices(searchAlias).execute().actionGet(fessConfig.getIndexIndicesTimeout());
         final String[] searchIndices = response2.indices();
 
-        IndicesAliasesRequestBuilder builder =
+        final IndicesAliasesRequestBuilder builder =
                 client.admin().indices().prepareAliases().addAlias(newIndex, updateAlias).addAlias(newIndex, searchAlias);
-        for (String index : updateIndices) {
+        for (final String index : updateIndices) {
             builder.removeAlias(index, updateAlias);
         }
-        for (String index : searchIndices) {
+        for (final String index : searchIndices) {
             builder.removeAlias(index, searchAlias);
         }
-        IndicesAliasesResponse response = builder.execute().actionGet(fessConfig.getIndexIndicesTimeout());
+        final IndicesAliasesResponse response = builder.execute().actionGet(fessConfig.getIndexIndicesTimeout());
         return response.isAcknowledged();
     }
 
@@ -1413,12 +1413,12 @@ public class FessEsClient implements Client {
     }
 
     @Override
-    public ActionFuture<FieldCapabilitiesResponse> fieldCaps(FieldCapabilitiesRequest request) {
+    public ActionFuture<FieldCapabilitiesResponse> fieldCaps(final FieldCapabilitiesRequest request) {
         return client.fieldCaps(request);
     }
 
     @Override
-    public void fieldCaps(FieldCapabilitiesRequest request, ActionListener<FieldCapabilitiesResponse> listener) {
+    public void fieldCaps(final FieldCapabilitiesRequest request, final ActionListener<FieldCapabilitiesResponse> listener) {
         client.fieldCaps(request, listener);
     }
 
diff --git a/src/main/java/org/codelibs/fess/exception/ContentNotFoundException.java b/src/main/java/org/codelibs/fess/exception/ContentNotFoundException.java
index 26a3487c4..054ac502d 100644
--- a/src/main/java/org/codelibs/fess/exception/ContentNotFoundException.java
+++ b/src/main/java/org/codelibs/fess/exception/ContentNotFoundException.java
@@ -19,7 +19,7 @@ public class ContentNotFoundException extends FessSystemException {
 
     private static final long serialVersionUID = 1L;
 
-    public ContentNotFoundException(String url) {
+    public ContentNotFoundException(final String url) {
         super("Not Found: " + url, false, false);
     }
 
diff --git a/src/main/java/org/codelibs/fess/mylasta/direction/FessProp.java b/src/main/java/org/codelibs/fess/mylasta/direction/FessProp.java
index e18aa1cfe..dca64120b 100644
--- a/src/main/java/org/codelibs/fess/mylasta/direction/FessProp.java
+++ b/src/main/java/org/codelibs/fess/mylasta/direction/FessProp.java
@@ -1568,7 +1568,7 @@ public interface FessProp {
                 if (v1.length == 2) {
                     final String[] v2 = v1[0].split(":");
                     if (v2.length == 2) {
-                        return new Tuple3<String, String, String>(v2[0].trim(), v2[0].trim(), "/" + v1[1].trim());
+                        return new Tuple3<>(v2[0].trim(), v2[0].trim(), "/" + v1[1].trim());
                     }
                 }
                 return null;
@@ -1577,7 +1577,7 @@ public interface FessProp {
         }
         final Tuple3<String, String, String>[] vHosts = hosts;
         return LaRequestUtil.getOptionalRequest().map(req -> {
-            for (Tuple3<String, String, String> host : vHosts) {
+            for (final Tuple3<String, String, String> host : vHosts) {
                 final String headerValue = req.getHeader(host.getValue1());
                 if (host.getValue2().equalsIgnoreCase(headerValue)) {
                     return new HtmlNext(host.getValue3() + page.getRoutingPath());
@@ -1597,7 +1597,7 @@ public interface FessProp {
                             stream -> stream.filter(StringUtil::isNotBlank).mapToInt(Integer::parseInt).toArray());
             propMap.put(CRAWLER_FAILURE_URL_STATUS_CODES, codes);
         }
-        for (int v : codes) {
+        for (final int v : codes) {
             if (v == code) {
                 return true;
             }
diff --git a/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java b/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java
index 55d152b8e..844392074 100644
--- a/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java
+++ b/src/main/java/org/codelibs/fess/thumbnail/ThumbnailManager.java
@@ -212,7 +212,7 @@ public class ThumbnailManager {
                     if (!generator.generate(entity.getThumbnailId(), entity.getUrl(), outputFile)) {
                         new File(outputFile.getAbsolutePath() + NOIMAGE_FILE_SUFFIX).setLastModified(System.currentTimeMillis());
                     } else {
-                        long interval = fessConfig.getThumbnailGeneratorIntervalAsInteger().longValue();
+                        final long interval = fessConfig.getThumbnailGeneratorIntervalAsInteger().longValue();
                         if (interval > 0) {
                             Thread.sleep(interval);
                         }
diff --git a/src/main/java/org/codelibs/fess/thumbnail/impl/BaseThumbnailGenerator.java b/src/main/java/org/codelibs/fess/thumbnail/impl/BaseThumbnailGenerator.java
index 81a6c0c27..2c0a2466f 100644
--- a/src/main/java/org/codelibs/fess/thumbnail/impl/BaseThumbnailGenerator.java
+++ b/src/main/java/org/codelibs/fess/thumbnail/impl/BaseThumbnailGenerator.java
@@ -116,7 +116,7 @@ public abstract class BaseThumbnailGenerator implements ThumbnailGenerator {
         try {
             ComponentUtil.getIndexingHelper().updateDocument(ComponentUtil.getFessEsClient(), thumbnailId,
                     fessConfig.getIndexFieldThumbnail(), null);
-        } catch (Exception e) {
+        } catch (final Exception e) {
             logger.warn("Failed to update thumbnail field at " + url, e);
         }
     }
diff --git a/src/main/java/org/codelibs/fess/thumbnail/impl/HtmlTagBasedGenerator.java b/src/main/java/org/codelibs/fess/thumbnail/impl/HtmlTagBasedGenerator.java
index eaf91379b..f86f21f67 100644
--- a/src/main/java/org/codelibs/fess/thumbnail/impl/HtmlTagBasedGenerator.java
+++ b/src/main/java/org/codelibs/fess/thumbnail/impl/HtmlTagBasedGenerator.java
@@ -124,9 +124,8 @@ public class HtmlTagBasedGenerator extends BaseThumbnailGenerator {
                 final BufferedImage image = reader.read(0, param);
                 final int thumbnailWidth = fessConfig.getThumbnailHtmlImageThumbnailWidthAsInteger();
                 final int thumbnailHeight =
-                        (int) (((float) (height > width ? width : height))
-                                * fessConfig.getThumbnailHtmlImageThumbnailWidthAsInteger().floatValue() / (float) width);
-                BufferedImage thumbnail = new BufferedImage(thumbnailWidth, thumbnailHeight, image.getType());
+                        (int) ((height > width ? width : height) * fessConfig.getThumbnailHtmlImageThumbnailWidthAsInteger().floatValue() / width);
+                final BufferedImage thumbnail = new BufferedImage(thumbnailWidth, thumbnailHeight, image.getType());
                 thumbnail.getGraphics().drawImage(image.getScaledInstance(thumbnailWidth, thumbnailHeight, Image.SCALE_AREA_AVERAGING), 0,
                         0, thumbnailWidth, thumbnailHeight, null);
                 ImageIO.write(thumbnail, fessConfig.getThumbnailHtmlImageFormat(), outputFile);