AssignmentOrReturnOfFieldWithMutableType: Guava test & field type check (IDEA-191042)

plugins/InspectionGadgets/src/com/siyeh/ig/encapsulation/AssignmentOrReturnOfFieldWithMutableTypeInspection.java

@@ -145,7 +145,9 @@ public class AssignmentOrReturnOfFieldWithMutableTypeInspection extends BaseInsp
       if (field == null) return;
       final String type = TypeUtils.expressionHasTypeOrSubtype(returnValue, MUTABLE_TYPES);
       if (type == null && !(returnValue.getType() instanceof PsiArrayType)) return;
-      if (CollectionUtils.isConstantEmptyArray(field) || Mutability.getMutability(field).isUnmodifiable()) return;
+      if (CollectionUtils.isConstantEmptyArray(field) ||
+          ClassUtils.isImmutable(field.getType()) ||
+          Mutability.getMutability(field).isUnmodifiable()) return;
       registerError(returnValue, field, returnValue, type, Boolean.FALSE);
     }
   }

plugins/InspectionGadgets/test/com/siyeh/igtest/encapsulation/assignment_or_return_of_field_with_mutable_type/AssignmentOrReturnOfFieldWithMutableType.java

@@ -1,6 +1,7 @@
 package com.siyeh.igtest.encapsulation;
 
 import java.util.*;
+import com.google.common.collect.*;
 
 public class AssignmentOrReturnOfFieldWithMutableType
 {
@@ -151,4 +152,12 @@ class ImmutableTest {
     public List<String> getList() {
         return list;
     }
+}
+
+class GuavaTest {
+    private final ImmutableList<?> list = ImmutableList.of();
+
+    public ImmutableList<?> getList() {
+        return list;
+    }
 }

plugins/InspectionGadgets/testsrc/com/siyeh/ig/encapsulation/AssignmentOrReturnOfFieldWithMutableTypeInspectionTest.java

@@ -22,6 +22,19 @@ public class AssignmentOrReturnOfFieldWithMutableTypeInspectionTest extends Ligh
     }
   };
 
+  @Override
+  protected String[] getEnvironmentClasses() {
+    return new String[] {
+      "package com.google.common.collect;\n" +
+      "\n" +
+      "import java.util.List;\n" +
+      "\n" +
+      "public class ImmutableList<E> implements List<E> {\n" +
+      "  public static ImmutableList<?> of() {return new ImmutableList<>();}\n" +
+      "}"
+    };
+  }
+
   @NotNull
   @Override
   protected LightProjectDescriptor getProjectDescriptor() {