java: report unused utility classes with unused methods as unused (IDEA-217378)

for "Unused declaration" inspection in batch mode

GitOrigin-RevId: f19b13dd262f0059adc4c08237e620ec8256e013

java/java-analysis-impl/src/com/intellij/codeInspection/reference/RefClassImpl.java

@@ -140,7 +140,7 @@ public final class RefClassImpl extends RefJavaElementImpl implements RefClass {
         if (uMethod.isConstructor()) {
           constructorSeen = true;
           final List<UParameter> parameters = uMethod.getUastParameters();
-          if (!parameters.isEmpty()|| uMethod.getVisibility() != UastVisibility.PRIVATE) {
+          if (!parameters.isEmpty() || uMethod.getVisibility() != UastVisibility.PRIVATE) {
             utilityClass = false;
           }
 
@@ -439,11 +439,6 @@ public final class RefClassImpl extends RefJavaElementImpl implements RefClass {
     return checkFlag(IS_ANNOTATION_MASK);
   }
 
-  @Override
-  public boolean isSuspicious() {
-    return !(isUtilityClass() && getOutReferences().isEmpty()) && super.isSuspicious();
-  }
-
   @Override
   public boolean isUtilityClass() {
     return checkFlag(IS_UTILITY_MASK);
@@ -527,10 +522,10 @@ public final class RefClassImpl extends RefJavaElementImpl implements RefClass {
     if (super.isReferenced()) return true;
 
     if (isInterface()) {
-      if (!getDerivedReferences().isEmpty()) return true;
+      return !getDerivedReferences().isEmpty();
     }
     else if (isAbstract()) {
-      if (!getSubClasses().isEmpty()) return true;
+      return !getSubClasses().isEmpty();
     }
 
     return false;
@@ -541,10 +536,10 @@ public final class RefClassImpl extends RefJavaElementImpl implements RefClass {
     if (super.hasSuspiciousCallers()) return true;
 
     if (isInterface()) {
-      if (!getDerivedReferences().isEmpty()) return true;
+      return !getDerivedReferences().isEmpty();
     }
     else if (isAbstract()) {
-      if (!getSubClasses().isEmpty()) return true;
+      return !getSubClasses().isEmpty();
     }
 
     return false;

java/java-tests/testData/inspection/deadCode/utilityClass/expected.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>Example.java</file>
+    <line>4</line>
+    <description>Method is never used.</description>
+  </problem>
+  <problem>
+    <file>Example.java</file>
+    <line>3</line>
+    <description>No class references have been found. Class static initializer is not reachable.</description>
+  </problem>
+</problems>

java/java-tests/testData/inspection/deadCode/utilityClass/src/Example.java

@@ -0,0 +1,5 @@
+package deadCode.utilityClass.src;
+
+public class Example {
+  public static void test() {}
+} 

java/java-tests/testSrc/com/intellij/java/codeInspection/UnusedDeclarationInspectionTest.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.java.codeInspection;
 
 import com.intellij.codeInspection.ex.EntryPointsManagerBase;
@@ -267,6 +267,10 @@ public class UnusedDeclarationInspectionTest extends AbstractUnusedDeclarationTe
     doTest();
   }
 
+  public void testUtilityClass() {
+    doTest();
+  }
+
   public void testJunitMethodSource() {doTest();}
 
   public void testImplicitClass() {