minor fixes

kafka-ui-api/src/main/java/com/provectus/kafka/ui/service/acl/AclCsv.java

@@ -65,7 +65,7 @@ public class AclCsv {
   public static Collection<AclBinding> parseCsv(String csvString) {
     String[] lines = csvString.split(LINE_SEPARATOR);
     if (lines.length == 0) {
-      throw new ValidationException("Error parsing ACL csv file: ");
+      throw new ValidationException("Error parsing ACL csv file: no lines in file");
     }
     boolean firstLineIsHeader = HEADER.equalsIgnoreCase(lines[0].trim().replace(" ", ""));
     Set<AclBinding> result = new HashSet<>();

kafka-ui-api/src/test/java/com/provectus/kafka/ui/service/acl/AclCsvTest.java

@@ -3,6 +3,7 @@ package com.provectus.kafka.ui.service.acl;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
+import com.provectus.kafka.ui.exception.ValidationException;
 import java.util.Collection;
 import java.util.List;
 import org.apache.kafka.common.acl.AccessControlEntry;
@@ -55,7 +56,8 @@ class AclCsvTest {
       "User:test1,TOPIC,LITERAL,*,READ,ILLEGAL,*"
   })
   void throwsExceptionForInvalidInputCsv(String csvString) {
-    assertThatThrownBy(() -> AclCsv.parseCsv(csvString)).isNotNull();
+    assertThatThrownBy(() -> AclCsv.parseCsv(csvString))
+        .isInstanceOf(ValidationException.class);
   }
 
   @Test
@@ -65,4 +67,4 @@ class AclCsvTest {
     assertThat(parsedBindings).containsExactlyInAnyOrderElementsOf(TEST_BINDINGS);
   }
 
-}
+}