issue-122: updated add1GetterMethod logic in useImmutableCollections=true case (#138)

record-builder-processor/src/main/java/io/soabase/recordbuilder/processor/InternalRecordBuilderProcessor.java

@@ -938,11 +938,23 @@ class InternalRecordBuilderProcessor {
                 .addModifiers(Modifier.PUBLIC)
                 .addAnnotation(generatedRecordBuilderAnnotation)
                 .returns(component.typeName())
-                .addStatement("return $L", component.name());
+                .addCode(checkReturnShim(component));
         addAccessorAnnotations(component, methodSpecBuilder, __ -> true);
         builder.addMethod(methodSpecBuilder.build());
     }
 
+    private CodeBlock checkReturnShim(RecordClassType component) {
+        var codeBuilder = CodeBlock.builder();
+        if (collectionBuilderUtils.isImmutableCollection(component)) {
+            codeBuilder.add("return ");
+            collectionBuilderUtils.addShimCall(codeBuilder, component);
+            codeBuilder.add(";");
+        } else {
+            codeBuilder.addStatement("return $L", component.name());
+        }
+        return codeBuilder.build();
+    }
+
     private void add1SetterMethod(RecordClassType component) {
         /*
             For a single record component, add a setter similar to:

record-builder-test/src/test/java/io/soabase/recordbuilder/test/TestCollectionsBuilder.java

@@ -0,0 +1,36 @@
+/**
+ * Copyright 2019 Jordan Zimmerman
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.soabase.recordbuilder.test;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class TestCollectionsBuilder {
+
+    @Test
+    void testCollectionsBuilderReturnNonNullEmptyCollections() {
+        CollectionRecordBuilder<Object, Point> builder = CollectionRecordBuilder.builder();
+
+        Assertions.assertNotNull(builder.l());
+        Assertions.assertTrue(builder.l().isEmpty());
+        Assertions.assertNotNull(builder.c());
+        Assertions.assertTrue(builder.c().isEmpty());
+        Assertions.assertNotNull(builder.m());
+        Assertions.assertTrue(builder.m().isEmpty());
+        Assertions.assertNotNull(builder.s());
+        Assertions.assertTrue(builder.s().isEmpty());
+    }
+}