Safely ignore enums in native type extensions

Ref: #1077
PiperOrigin-RevId: 927414521

Author: l46kok

extensions/src/main/java/dev/cel/extensions/CelNativeTypesExtensions.java

@@ -82,6 +82,10 @@ public final class CelNativeTypesExtensions implements CelCompilerLibrary, CelRu
   private static final ImmutableSet<String> OBJECT_METHOD_NAMES =
       stream(Object.class.getDeclaredMethods()).map(Method::getName).collect(toImmutableSet());
 
+  // Set of all standard java.lang.Enum method names.
+  private static final ImmutableSet<String> ENUM_METHOD_NAMES =
+      stream(Enum.class.getDeclaredMethods()).map(Method::getName).collect(toImmutableSet());
+
   private static final ImmutableMap<Class<?>, CelType> JAVA_TO_CEL_TYPE_MAP =
       ImmutableMap.<Class<?>, CelType>builder()
           .put(boolean.class, SimpleType.BOOL)
@@ -603,7 +607,7 @@ private static boolean isGetter(Method method) {
         return false;
       }
       String name = method.getName();
-      if (OBJECT_METHOD_NAMES.contains(name)) {
+      if (OBJECT_METHOD_NAMES.contains(name) || ENUM_METHOD_NAMES.contains(name)) {
         return false;
       }
       if (name.startsWith("get")) {

extensions/src/main/java/dev/cel/extensions/README.md

@@ -1122,6 +1122,7 @@ The type-mapping between Java and CEL is as follows:
 
 *   This is only supported for the planner runtime (e.g., `CelRuntimeFactory.plannerRuntimeBuilder()`).
 *   Native Java arrays (except `byte[]`) are not supported. Use `java.util.List` instead.
+*   Java `enum` properties are not currently supported and will be safely ignored during scanning.
 *   If there is a name collision with a Protobuf type, the protobuf type will take precedence.
 *   Instantiating new struct values (e.g., `Account{id: 1234}`) requires the class to have a no-argument constructor (public, protected, package-private, or private).
 *   Final fields are supported only in a **read-only** capacity; they cannot be populated when instantiating new struct values.

extensions/src/test/java/dev/cel/extensions/CelNativeTypesExtensionsTest.java

@@ -89,7 +89,8 @@ public final class CelNativeTypesExtensionsTest {
           TestNestedSimplePojo.class,
           TestGetterFieldTypeMismatchPojo.class,
           TestAbstractPojo.class,
-          TestURLPojo.class);
+          TestURLPojo.class,
+          PojoWithEnum.class);
 
   private static final Cel CEL =
       CelFactory.plannerCelBuilder()
@@ -1346,4 +1347,26 @@ public String getMismatchField() {
       return "mismatch";
     }
   }
+
+  public enum TestEnum {
+    FOO,
+    BAR;
+  }
+
+  public static class PojoWithEnum {
+    private TestEnum enumVal = TestEnum.FOO;
+
+    public TestEnum getEnumVal() {
+      return enumVal;
+    }
+
+    public void setEnumVal(TestEnum val) {
+      this.enumVal = val;
+    }
+  }
+
+  @Test
+  public void nativeTypes_enumSafelyIgnored() throws Exception {
+    assertThat(eval("PojoWithEnum{}.enumVal")).isNotNull();
+  }
 }