[ggj][ast] feat: add ValueExpr.createNullExpr() convenience wrapper

src/main/java/com/google/api/generator/engine/ast/ValueExpr.java

@@ -34,6 +34,10 @@ public static ValueExpr withValue(Value value) {
     return builder().setValue(value).build();
   }
 
+  public static ValueExpr createNullExpr() {
+    return withValue(NullObjectValue.create());
+  }
+
   public static Builder builder() {
     return new AutoValue_ValueExpr.Builder();
   }

src/main/java/com/google/api/generator/gapic/composer/BatchingDescriptorComposer.java

@@ -29,7 +29,6 @@
 import com.google.api.generator.engine.ast.MethodDefinition;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
 import com.google.api.generator.engine.ast.NewObjectExpr;
-import com.google.api.generator.engine.ast.NullObjectValue;
 import com.google.api.generator.engine.ast.PrimitiveValue;
 import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.RelationalOperationExpr;
@@ -205,7 +204,7 @@ private static MethodDefinition createGetRequestBuilderMethod(
                     IfStatement.builder()
                         .setConditionExpr(
                             RelationalOperationExpr.equalToWithExprs(
-                                builderVarExpr, ValueExpr.withValue(NullObjectValue.create())))
+                                builderVarExpr, ValueExpr.createNullExpr()))
                         .setBody(Arrays.asList(ExprStatement.withExpr(toBuilderExpr)))
                         .setElseBody(Arrays.asList(ExprStatement.withExpr(addAllExpr)))
                         .build()))

src/main/java/com/google/api/generator/gapic/composer/ResourceNameHelperClassComposer.java

@@ -31,7 +31,6 @@
 import com.google.api.generator.engine.ast.MethodDefinition;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
 import com.google.api.generator.engine.ast.NewObjectExpr;
-import com.google.api.generator.engine.ast.NullObjectValue;
 import com.google.api.generator.engine.ast.PrimitiveValue;
 import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.RelationalOperationExpr;
@@ -288,7 +287,7 @@ private static List<MethodDefinition> createConstructorMethods(
     boolean hasVariants = tokenHierarchies.size() > 1;
 
     List<MethodDefinition> javaMethods = new ArrayList<>();
-    final ValueExpr nullExpr = ValueExpr.withValue(NullObjectValue.create());
+    final ValueExpr nullExpr = ValueExpr.createNullExpr();
     Function<String, AssignmentExpr> assignTokenToNullExpr =
         t ->
             AssignmentExpr.builder()
@@ -622,8 +621,7 @@ private static MethodDefinition createParseMethod(
                     .build())
             .setBody(
                 Arrays.asList(
-                    ExprStatement.withExpr(
-                        ReturnExpr.withExpr(ValueExpr.withValue(NullObjectValue.create())))))
+                    ExprStatement.withExpr(ReturnExpr.withExpr(ValueExpr.createNullExpr()))))
             .build());
 
     List<Expr> formattedStringArgList = Arrays.asList(formattedStringArgExpr);
@@ -864,8 +862,7 @@ private static MethodDefinition createToStringListMethod(TypeNode thisClassType)
             Variable.builder().setName("value").setType(thisClassType).build());
     // We use an equality check instead of Objects.isNull() for Java 7 compatibility.
     Expr isNullCheck =
-        RelationalOperationExpr.equalToWithExprs(
-            valueVarExpr, ValueExpr.withValue(NullObjectValue.create()));
+        RelationalOperationExpr.equalToWithExprs(valueVarExpr, ValueExpr.createNullExpr());
     Statement listAddEmptyStringStatement =
         ExprStatement.withExpr(
             MethodInvocationExpr.builder()
@@ -1002,8 +999,7 @@ private static MethodDefinition createGetFieldValuesMapMethod(
               .setArguments(ValueExpr.withValue(tokenStrVal), tokenVarExpr)
               .build();
       Expr notNullCheckExpr =
-          RelationalOperationExpr.notEqualToWithExprs(
-              tokenVarExpr, ValueExpr.withValue(NullObjectValue.create()));
+          RelationalOperationExpr.notEqualToWithExprs(tokenVarExpr, ValueExpr.createNullExpr());
       tokenIfStatements.add(
           IfStatement.builder()
               .setConditionExpr(notNullCheckExpr)
@@ -1031,8 +1027,7 @@ private static MethodDefinition createGetFieldValuesMapMethod(
 
     // Middle if-block, i.e. `if (fieldValuesMap == null)`.
     Expr fieldValuesMapNullCheckExpr =
-        RelationalOperationExpr.equalToWithExprs(
-            fieldValuesMapVarExpr, ValueExpr.withValue(NullObjectValue.create()));
+        RelationalOperationExpr.equalToWithExprs(fieldValuesMapVarExpr, ValueExpr.createNullExpr());
     IfStatement fieldValuesMapIfStatement =
         IfStatement.builder()
             .setConditionExpr(fieldValuesMapNullCheckExpr)
@@ -1125,8 +1120,7 @@ private static MethodDefinition createToStringMethod(
     VariableExpr fixedValueVarExpr = FIXED_CLASS_VARS.get("fixedValue");
     // Code:  return fixedValue != null ? fixedValue : pathTemplate.instantiate(getFieldValuesMap())
     Expr fixedValueNullCheck =
-        RelationalOperationExpr.notEqualToWithExprs(
-            fixedValueVarExpr, ValueExpr.withValue(NullObjectValue.create()));
+        RelationalOperationExpr.notEqualToWithExprs(fixedValueVarExpr, ValueExpr.createNullExpr());
 
     MethodInvocationExpr instantiateExpr =
         MethodInvocationExpr.builder()
@@ -1171,8 +1165,7 @@ private static MethodDefinition createEqualsMethod(
     RelationalOperationExpr oEqualsThisExpr =
         RelationalOperationExpr.equalToWithExprs(argVarExpr, thisValueExpr);
     RelationalOperationExpr oNotEqualsNullExpr =
-        RelationalOperationExpr.notEqualToWithExprs(
-            argVarExpr, ValueExpr.withValue(NullObjectValue.create()));
+        RelationalOperationExpr.notEqualToWithExprs(argVarExpr, ValueExpr.createNullExpr());
     MethodInvocationExpr getClassMethodInvocationExpr =
         MethodInvocationExpr.builder().setMethodName("getClass").build();
     RelationalOperationExpr getClassEqualsExpr =

src/main/java/com/google/api/generator/gapic/composer/RetrySettingsComposer.java

@@ -30,7 +30,6 @@
 import com.google.api.generator.engine.ast.Expr;
 import com.google.api.generator.engine.ast.ExprStatement;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
-import com.google.api.generator.engine.ast.NullObjectValue;
 import com.google.api.generator.engine.ast.PrimitiveValue;
 import com.google.api.generator.engine.ast.StringObjectValue;
 import com.google.api.generator.engine.ast.TypeNode;
@@ -108,7 +107,7 @@ public static BlockStatement createRetryParamDefinitionsBlock(
     bodyExprs.add(
         AssignmentExpr.builder()
             .setVariableExpr(settingsVarExpr.toBuilder().setIsDecl(true).build())
-            .setValueExpr(ValueExpr.withValue(NullObjectValue.create()))
+            .setValueExpr(ValueExpr.createNullExpr())
             .build());
 
     // Build the settings object for each config.

src/main/java/com/google/api/generator/gapic/composer/ServiceClientClassComposer.java

@@ -40,7 +40,6 @@
 import com.google.api.generator.engine.ast.MethodDefinition;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
 import com.google.api.generator.engine.ast.NewObjectExpr;
-import com.google.api.generator.engine.ast.NullObjectValue;
 import com.google.api.generator.engine.ast.PrimitiveValue;
 import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.ReferenceConstructorExpr;
@@ -390,7 +389,7 @@ private static List<MethodDefinition> createConstructorMethods(
     ctorAssignmentExprs.add(
         AssignmentExpr.builder()
             .setVariableExpr(settingsVarExpr.toBuilder().setExprReferenceExpr(thisExpr).build())
-            .setValueExpr(ValueExpr.withValue(NullObjectValue.create()))
+            .setValueExpr(ValueExpr.createNullExpr())
             .build());
     ctorAssignmentExprs.add(
         AssignmentExpr.builder()
@@ -1125,7 +1124,7 @@ private static ClassDefinition createNestedRpcPageClass(
             .build();
 
     // createEmptyPage method.
-    ValueExpr nullExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr nullExpr = ValueExpr.createNullExpr();
     MethodDefinition createEmptyPageMethod =
         MethodDefinition.builder()
             .setScope(ScopeNode.PRIVATE)
@@ -1276,7 +1275,7 @@ private static ClassDefinition createNestedRpcFixedSizeCollectionClass(
                 NewObjectExpr.builder()
                     .setType(classType)
                     .setArguments(
-                        ValueExpr.withValue(NullObjectValue.create()),
+                        ValueExpr.createNullExpr(),
                         ValueExpr.withValue(
                             PrimitiveValue.builder().setType(TypeNode.INT).setValue("0").build()))
                     .build())
@@ -1348,7 +1347,7 @@ static MethodInvocationExpr buildNestedSetterInvocationExpr(
         VariableExpr.withVariable(
             Variable.builder().setName(argumentName).setType(argumentType).build());
     if (argument.isResourceNameHelper()) {
-      Expr nullExpr = ValueExpr.withValue(NullObjectValue.create());
+      Expr nullExpr = ValueExpr.createNullExpr();
       Expr isNullCheckExpr = RelationalOperationExpr.equalToWithExprs(argVarExpr, nullExpr);
       MethodInvocationExpr toStringExpr =
           MethodInvocationExpr.builder()

src/main/java/com/google/api/generator/gapic/composer/ServiceSettingsClassComposer.java

@@ -39,7 +39,6 @@
 import com.google.api.generator.engine.ast.MethodDefinition;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
 import com.google.api.generator.engine.ast.NewObjectExpr;
-import com.google.api.generator.engine.ast.NullObjectValue;
 import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.ReferenceConstructorExpr;
 import com.google.api.generator.engine.ast.ScopeNode;
@@ -452,7 +451,7 @@ private static List<MethodDefinition> createNestedBuilderConstructorMethods(
                             .setArguments(
                                 CastExpr.builder()
                                     .setType(staticTypes.get("ClientContext"))
-                                    .setExpr(ValueExpr.withValue(NullObjectValue.create()))
+                                    .setExpr(ValueExpr.createNullExpr())
                                     .build())
                             .build())))
             .build();

src/main/java/com/google/api/generator/gapic/composer/ServiceStubSettingsClassComposer.java

@@ -65,7 +65,6 @@
 import com.google.api.generator.engine.ast.MethodDefinition;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
 import com.google.api.generator.engine.ast.NewObjectExpr;
-import com.google.api.generator.engine.ast.NullObjectValue;
 import com.google.api.generator.engine.ast.Reference;
 import com.google.api.generator.engine.ast.ReferenceConstructorExpr;
 import com.google.api.generator.engine.ast.RelationalOperationExpr;
@@ -546,8 +545,7 @@ private static Expr createPagedListDescriptorAssignExpr(
             .setReturnType(returnType)
             .build();
     Expr conditionExpr =
-        RelationalOperationExpr.equalToWithExprs(
-            getResponsesListExpr, ValueExpr.withValue(NullObjectValue.create()));
+        RelationalOperationExpr.equalToWithExprs(getResponsesListExpr, ValueExpr.createNullExpr());
     Expr thenExpr =
         MethodInvocationExpr.builder()
             .setStaticReferenceType(
@@ -1345,7 +1343,7 @@ private static List<MethodDefinition> createNestedClassConstructorMethods(
                             .setArguments(
                                 CastExpr.builder()
                                     .setType(STATIC_TYPES.get("ClientContext"))
-                                    .setExpr(ValueExpr.withValue(NullObjectValue.create()))
+                                    .setExpr(ValueExpr.createNullExpr())
                                     .build())
                             .build())))
             .build());
@@ -1597,7 +1595,7 @@ private static MethodDefinition createNestedClassCreateDefaultMethod(
                         .setArguments(
                             CastExpr.builder()
                                 .setType(STATIC_TYPES.get("ClientContext"))
-                                .setExpr(ValueExpr.withValue(NullObjectValue.create()))
+                                .setExpr(ValueExpr.createNullExpr())
                                 .build())
                         .build())
                 .build()));

src/test/java/com/google/api/generator/engine/ast/ArithmeticOperationExprTest.java

@@ -38,7 +38,7 @@ public void concatOperator_validWithNull() {
     // Type-checking for String variable x and null object value.
     VariableExpr lhsExpr =
         VariableExpr.withVariable(Variable.builder().setType(TypeNode.STRING).setName("x").build());
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     ArithmeticOperationExpr.concatWithExprs(lhsExpr, rhsExpr);
     // No exception thrown, so we succeeded.
   }

src/test/java/com/google/api/generator/engine/ast/AssignmentOperationExprTest.java

@@ -349,7 +349,7 @@ public void invalidMultiplyAndAssignmentOperationExpr_floatBoxedWithObjectType()
   public void invalidMultiplyAndAssignmentOperationExpr_floatBoxedWithNullType() {
     // No need swap case.
     VariableExpr lhsExpr = createVariableExpr(TypeNode.FLOAT_OBJECT, "x");
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> AssignmentOperationExpr.multiplyAssignmentWithExprs(lhsExpr, rhsExpr));
@@ -463,7 +463,7 @@ public void invalidMultiplyAndAssignmentOperationExpr_doubleBoxedWithReferenceTy
   public void invalidMultiplyAndAssignmentOperationExpr_doubleBoxedWithNullType() {
     // No need swap case.
     VariableExpr lhsExpr = createVariableExpr(TypeNode.DOUBLE_OBJECT, "x");
-    ValueExpr valueExprExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr valueExprExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> AssignmentOperationExpr.multiplyAssignmentWithExprs(lhsExpr, valueExprExpr));
@@ -533,7 +533,7 @@ public void invalidMultiplyAndAssignmentOperationExpr_longBoxedWithDoubleType()
   public void invalidMultiplyAndAssignmentOperationExpr_longBoxedWithNullType() {
     // Swap test case in "invalidMultiplyAndAssignmentOperationExpr_nullWithLongBoxedType".
     VariableExpr lhsExpr = createVariableExpr(TypeNode.LONG_OBJECT, "x");
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> AssignmentOperationExpr.multiplyAssignmentWithExprs(lhsExpr, rhsExpr));
@@ -715,7 +715,7 @@ public void invalidXorAssignmentOperationExpr_booleanWithReferencedTypes() {
   public void invalidXorAssignmentOperationExpr_booleanWithNullTypes() {
     // No valid swap case.
     VariableExpr lhsExpr = createVariableExpr(TypeNode.BOOLEAN, "x");
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> AssignmentOperationExpr.xorAssignmentWithExprs(lhsExpr, rhsExpr));
@@ -894,7 +894,7 @@ public void invalidXorAssignmentOperationExpr_integerWithBooleanTypes() {
   public void invalidXorAssignmentOperationExpr_integerWithNullTypes() {
     // No need swap case.
     VariableExpr lhsExpr = createVariableExpr(TypeNode.INT, "x");
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> AssignmentOperationExpr.xorAssignmentWithExprs(lhsExpr, rhsExpr));
@@ -1091,7 +1091,7 @@ public void invalidXorAssignmentOperationExpr_integerBoxedTypeWithBooleanTypes()
   public void invalidXorAssignmentOperationExpr_integerBoxedWithNullTypes() {
     // No need swap case.
     VariableExpr lhsExpr = createVariableExpr(TypeNode.INT_OBJECT, "x");
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> AssignmentOperationExpr.xorAssignmentWithExprs(lhsExpr, rhsExpr));

src/test/java/com/google/api/generator/engine/ast/CastExprTest.java

@@ -36,7 +36,7 @@ public void validCastExpr_basicNull() {
     VariableExpr variableExpr = VariableExpr.builder().setVariable(variable).build();
     CastExpr.builder()
         .setType(TypeNode.withReference(ConcreteReference.withClazz(Object.class)))
-        .setExpr(ValueExpr.withValue(NullObjectValue.create()))
+        .setExpr(ValueExpr.createNullExpr())
         .build();
     // No exception thrown, so we succeeded.
   }

src/test/java/com/google/api/generator/engine/ast/LogicalOperationExprTest.java

@@ -99,7 +99,7 @@ public void logicalOr_invalidNullType() {
     VariableExpr lhsExpr =
         VariableExpr.withVariable(
             Variable.builder().setType(TypeNode.BOOLEAN).setName("x").build());
-    ValueExpr rhsExpr = ValueExpr.withValue(NullObjectValue.create());
+    ValueExpr rhsExpr = ValueExpr.createNullExpr();
     assertThrows(
         IllegalStateException.class,
         () -> LogicalOperationExpr.logicalOrWithExprs(lhsExpr, rhsExpr));