diff --git a/tools/generator/GenBaseSupport.cs b/tools/generator/GenBaseSupport.cs
index ed91ebc12..481d9f978 100644
--- a/tools/generator/GenBaseSupport.cs
+++ b/tools/generator/GenBaseSupport.cs
@@ -204,7 +204,7 @@ public XmlGenBaseSupport (XmlElement pkg, XmlElement elem)
 				full_name = String.Format ("{0}.{1}{2}", ns, idx > 0 ? StringRocks.TypeToPascalCase (java_name.Substring (0, idx + 1)) : String.Empty, name);
 			}
 
-			obfuscated = IsObfuscatedName (java_name) && elem.XGetAttribute ("obfuscated") != "false";
+			obfuscated = IsObfuscatedName (pkg.ChildNodes.Count, java_name) && elem.XGetAttribute ("obfuscated") != "false";
 		}
 
 		public override bool IsAcw {
@@ -302,12 +302,21 @@ public override bool ValidateNamespace ()
 			return true;
 		}
 
-		bool IsObfuscatedName (String name)
+		bool IsObfuscatedName (int threshold, string name)
 		{
 			if (name.StartsWith ("R.", StringComparison.Ordinal))
 				return false;
 			int idx = name.LastIndexOf ('.');
 			string last = idx < 0 ? name : name.Substring (idx + 1);
+			// probably new proguard within Gradle tasks, used in recent GooglePlayServices in 2016 or later.
+			if (last.StartsWith ("zz", StringComparison.Ordinal))
+				return true;
+			// do not expect any name with more than 3 letters is an 'obfuscated' one.
+			if (last.Length > 3)
+				return false;
+			// Only short ones ('a', 'b', 'c' ... 'aa', 'ab', ... 'zzz') are the targets.
+			if (!(last.Length == 3 && threshold > 26*26 || last.Length == 2 && threshold > 26 || last.Length == 1))
+				return false;
 			if (last.Any (c => (c < 'a' || 'z' < c) && (c < '0' || '9' < c)))
 					return false;
 			return true;
diff --git a/tools/generator/Tests-Core/api-cp.xml b/tools/generator/Tests-Core/api-cp.xml
index c20b00f98..41015a890 100644
--- a/tools/generator/Tests-Core/api-cp.xml
+++ b/tools/generator/Tests-Core/api-cp.xml
@@ -3,6 +3,8 @@
   <package name="java.lang">
     <class abstract="false" deprecated="not deprecated" final="false" name="Object" static="false" visibility="public">
     </class>
+    <class abstract="false" deprecated="not deprecated" extends="java.lang.Object" extends-generic-aware="java.lang.Object" final="false" name="String" static="false" visibility="public">
+    </class>
   </package>
   <package name="xamarin.test.invalidnames">
     <class abstract="false" deprecated="not deprecated" extends="java.lang.Object" extends-generic-aware="java.lang.Object" final="false" name="InvalidNameMembers" static="false" visibility="public">
@@ -13,6 +15,12 @@
       <method abstract="false" deprecated="not deprecated" final="false" name="invalid$name" native="false" return="int" static="false" synchronized="false" visibility="public">
       </method>
     </class>
+    <class abstract="false" deprecated="not deprecated" extends="java.lang.Object" extends-generic-aware="java.lang.Object" final="false" name="a" static="false" visibility="public">
+    </class>
+    <class abstract="false" deprecated="not deprecated" extends="java.lang.Object" extends-generic-aware="java.lang.Object" final="false" name="in" static="false" visibility="public">
+    </class>
+    <class abstract="false" deprecated="not deprecated" extends="java.lang.Object" extends-generic-aware="java.lang.Object" final="false" name="zzTop" static="false" visibility="public">
+    </class>
   </package>
 </api>
 
diff --git a/tools/generator/Tests-Core/expected.cp/GeneratedFiles.projitems b/tools/generator/Tests-Core/expected.cp/GeneratedFiles.projitems
index 864450984..7e5723e9e 100644
--- a/tools/generator/Tests-Core/expected.cp/GeneratedFiles.projitems
+++ b/tools/generator/Tests-Core/expected.cp/GeneratedFiles.projitems
@@ -7,6 +7,8 @@
   <ItemGroup>
     <Compile Include="$(MSBuildThisFileDirectory)\Java.Interop.__TypeRegistrations.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)\Java.Lang.Object.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)\Java.Lang.String.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)\Xamarin.Test.Invalidnames.In.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)\Xamarin.Test.Invalidnames.InvalidNameMembers.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)\__NamespaceMapping__.cs" />
   </ItemGroup>
diff --git a/tools/generator/Tests-Core/expected.cp/Java.Interop.__TypeRegistrations.cs b/tools/generator/Tests-Core/expected.cp/Java.Interop.__TypeRegistrations.cs
index 6008ae6da..210cb8258 100644
--- a/tools/generator/Tests-Core/expected.cp/Java.Interop.__TypeRegistrations.cs
+++ b/tools/generator/Tests-Core/expected.cp/Java.Interop.__TypeRegistrations.cs
@@ -14,8 +14,10 @@ public static void RegisterPackages ()
 #endif // def MONODROID_TIMING
 			Java.Interop.TypeManager.RegisterPackages (
 					new string[]{
+						"xamarin/test/invalidnames",
 					},
 					new Converter<string, Type>[]{
+						lookup_xamarin_test_invalidnames_package,
 					});
 #if MONODROID_TIMING
 			var end = DateTime.Now;
@@ -30,5 +32,17 @@ static Type Lookup (string[] mappings, string javaType)
 				return null;
 			return Type.GetType (managedType);
 		}
+
+		static string[] package_xamarin_test_invalidnames_mappings;
+		static Type lookup_xamarin_test_invalidnames_package (string klass)
+		{
+			if (package_xamarin_test_invalidnames_mappings == null) {
+				package_xamarin_test_invalidnames_mappings = new string[]{
+					"xamarin/test/invalidnames/in:Xamarin.Test.Invalidnames.In",
+				};
+			}
+
+			return Lookup (package_xamarin_test_invalidnames_mappings, klass);
+		}
 	}
 }
diff --git a/tools/generator/Tests-Core/expected.cp/Java.Lang.String.cs b/tools/generator/Tests-Core/expected.cp/Java.Lang.String.cs
new file mode 100644
index 000000000..88051e79a
--- /dev/null
+++ b/tools/generator/Tests-Core/expected.cp/Java.Lang.String.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using Android.Runtime;
+
+namespace Java.Lang {
+
+	// Metadata.xml XPath class reference: path="/api/package[@name='java.lang']/class[@name='String']"
+	[global::Android.Runtime.Register ("java/lang/String", DoNotGenerateAcw=true)]
+	public partial class String : Java.Lang.Object {
+
+		protected String (IntPtr javaReference, JniHandleOwnership transfer) : base (javaReference, transfer) {}
+
+	}
+}
diff --git a/tools/generator/Tests-Core/expected.cp/Xamarin.Test.Invalidnames.In.cs b/tools/generator/Tests-Core/expected.cp/Xamarin.Test.Invalidnames.In.cs
new file mode 100644
index 000000000..1de9800a2
--- /dev/null
+++ b/tools/generator/Tests-Core/expected.cp/Xamarin.Test.Invalidnames.In.cs
@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using Android.Runtime;
+
+namespace Xamarin.Test.Invalidnames {
+
+	// Metadata.xml XPath class reference: path="/api/package[@name='xamarin.test.invalidnames']/class[@name='in']"
+	[global::Android.Runtime.Register ("xamarin/test/invalidnames/in", DoNotGenerateAcw=true)]
+	public partial class In : Java.Lang.Object {
+
+		protected In (IntPtr javaReference, JniHandleOwnership transfer) : base (javaReference, transfer) {}
+
+	}
+}