Move example plugin out of core

Summary:
We should not ship this as part of our distribution.
Just meant we had to bifurcate our unit tests which
is a bit awkward, but it works now.

Reviewed By: jknoxville

Differential Revision: D15146980

fbshipit-source-id: 496b000630bbfcaa663cddacb00550e1499a1279

android/src/test/java/com/facebook/flipper/plugins/example/ExampleFlipperPluginTest.java

@@ -1,38 +0,0 @@
-/*
- *  Copyright (c) 2018-present, Facebook, Inc.
- *
- *  This source code is licensed under the MIT license found in the LICENSE
- *  file in the root directory of this source tree.
- *
- */
-package com.facebook.flipper.plugins.example;
-
-import static org.hamcrest.CoreMatchers.hasItem;
-import static org.hamcrest.MatcherAssert.assertThat;
-
-import com.facebook.flipper.core.FlipperObject;
-import com.facebook.flipper.testing.FlipperConnectionMock;
-import com.facebook.flipper.testing.FlipperResponderMock;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.robolectric.RobolectricTestRunner;
-
-@RunWith(RobolectricTestRunner.class)
-public class ExampleFlipperPluginTest {
-
-  @Test
-  public void greetingTest() throws Exception {
-    final ExampleFlipperPlugin plugin = new ExampleFlipperPlugin();
-    final FlipperConnectionMock connection = new FlipperConnectionMock();
-    final FlipperResponderMock responder = new FlipperResponderMock();
-
-    plugin.onConnect(connection);
-    connection
-        .receivers
-        .get("displayMessage")
-        .onReceive(new FlipperObject.Builder().put("message", "test").build(), responder);
-
-    assertThat(
-        responder.successes, hasItem(new FlipperObject.Builder().put("greeting", "Hello").build()));
-  }
-}