diff --git a/google-http-client/src/main/java/com/google/api/client/util/ClassInfo.java b/google-http-client/src/main/java/com/google/api/client/util/ClassInfo.java
index f11f6ffb0..90c50058f 100644
--- a/google-http-client/src/main/java/com/google/api/client/util/ClassInfo.java
+++ b/google-http-client/src/main/java/com/google/api/client/util/ClassInfo.java
@@ -112,6 +112,22 @@ public final boolean getIgnoreCase() {
     return ignoreCase;
   }
 
+  /**
+   * Returns whether information for the given {@link FieldInfo#getName()} is available.
+   *
+   * @param name {@link FieldInfo#getName()} or {@code null}
+   * @return true if field info is available.
+   */
+  public boolean hasFieldInfo(String name) {
+    if (name != null) {
+      if (ignoreCase) {
+        name = name.toLowerCase(Locale.US);
+      }
+      name = name.intern();
+    }
+    return nameToFieldInfoMap.containsKey(name);
+  }
+
   /**
    * Returns the information for the given {@link FieldInfo#getName()}.
    *
diff --git a/google-http-client/src/main/java/com/google/api/client/util/GenericData.java b/google-http-client/src/main/java/com/google/api/client/util/GenericData.java
index 5ba12fe47..c6635f89e 100644
--- a/google-http-client/src/main/java/com/google/api/client/util/GenericData.java
+++ b/google-http-client/src/main/java/com/google/api/client/util/GenericData.java
@@ -74,6 +74,22 @@ public GenericData(EnumSet<Flags> flags) {
     classInfo = ClassInfo.of(getClass(), flags.contains(Flags.IGNORE_CASE));
   }
 
+  @Override
+  public final boolean containsKey(Object name) {
+    if (!(name instanceof String)) {
+      return false;
+    }
+    String fieldName = (String) name;
+    boolean hasFieldInfo = classInfo.hasFieldInfo(fieldName);
+    if (hasFieldInfo) {
+      return true;
+    }
+    if (classInfo.getIgnoreCase()) {
+      fieldName = fieldName.toLowerCase(Locale.US);
+    }
+    return unknownFields.containsKey(fieldName);
+  }
+
   @Override
   public final Object get(Object name) {
     if (!(name instanceof String)) {
diff --git a/google-http-client/src/test/java/com/google/api/client/util/ClassInfoTest.java b/google-http-client/src/test/java/com/google/api/client/util/ClassInfoTest.java
index d5e51d120..62d9fbcf8 100644
--- a/google-http-client/src/test/java/com/google/api/client/util/ClassInfoTest.java
+++ b/google-http-client/src/test/java/com/google/api/client/util/ClassInfoTest.java
@@ -58,6 +58,15 @@ public void testGetFieldInfo_enum() throws Exception {
     assertEquals(E.class.getField("VALUE"), classInfo.getFieldInfo("VALUE").getField());
   }
 
+  @Test
+  public void testHasFieldInfo_enum() throws Exception {
+    ClassInfo classInfo = ClassInfo.of(E.class);
+    assertFalse(classInfo.hasFieldInfo("wrong"));
+    assertTrue(classInfo.hasFieldInfo(null));
+    assertTrue(classInfo.hasFieldInfo("other"));
+    assertTrue(classInfo.hasFieldInfo("VALUE"));
+  }
+
   public class A {
     @Key String b;
 
diff --git a/google-http-client/src/test/java/com/google/api/client/util/GenericDataTest.java b/google-http-client/src/test/java/com/google/api/client/util/GenericDataTest.java
index 3b823d411..fd6547bb6 100644
--- a/google-http-client/src/test/java/com/google/api/client/util/GenericDataTest.java
+++ b/google-http-client/src/test/java/com/google/api/client/util/GenericDataTest.java
@@ -156,6 +156,7 @@ public void testPutIgnoreCase_class() {
   public void testGetIgnoreCase_class() {
     MyData data = new MyData();
     data.fieldA = "someValue";
+    assertTrue(data.containsKey("FIELDA"));
     assertEquals("someValue", data.get("FIELDA"));
   }
 
@@ -187,11 +188,14 @@ public void testPutIgnoreCase_unknownKey() {
   public void testGetIgnoreCase_unknownKey() {
     GenericData data = new GenericData(EnumSet.of(Flags.IGNORE_CASE));
     data.set("One", 1);
+    assertTrue(data.containsKey("ONE"));
     assertEquals(1, data.get("ONE"));
 
     data.set("one", 2);
+    assertTrue(data.containsKey("ONE"));
     assertEquals(2, data.get("ONE"));
 
+    assertFalse(data.containsKey("unknownKey"));
     assertEquals(null, data.get("unknownKey"));
   }