Creating Java FlipperMultiPlugin

Summary: Following the same logic as in the diff D63095017 and adding multiplugin on the java side. The logic of the methods are the same as in the C++ functions

Reviewed By: mkareta

Differential Revision: D63325568

fbshipit-source-id: 855708e6fc378715403ef3f398dc2c5c72cb1af3

android/src/main/java/com/facebook/flipper/core/FlipperMultiPlugin.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * 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.core;
+
+import java.util.List;
+
+/**
+ * A FlipperMultiPlugin is an object containing several plugins with the same identifiers exposeing
+ * an API to the Desktop Flipper application.
+ */
+public class FlipperMultiPlugin implements FlipperPlugin {
+  private List<FlipperPlugin> plugins;
+
+  public FlipperMultiPlugin(List<FlipperPlugin> plugins) {
+    this.plugins = plugins;
+    // Assert that all plugins have the same identifier.
+    String expectedIdentifier = plugins.get(0).getId();
+    boolean expectedRunInBackground = plugins.get(0).runInBackground();
+    for (FlipperPlugin plugin : plugins) {
+      assert plugin.getId().equals(expectedIdentifier);
+      assert plugin.runInBackground() == expectedRunInBackground;
+    }
+  }
+
+  public void addPlugin(FlipperPlugin plugin) {
+    // Assert that the new plugin has the same identifier as the existing plugins.
+    assert plugin.getId().equals(plugins.get(0).getId());
+    assert plugin.runInBackground() == plugins.get(0).runInBackground();
+    plugins.add(plugin);
+  }
+
+  @Override
+  public String getId() {
+    return plugins.get(0).getId();
+  }
+
+  @Override
+  public void onConnect(FlipperConnection conn) throws Exception {
+    // Forward the connection to each plugin.
+    for (FlipperPlugin plugin : plugins) {
+      plugin.onConnect(conn);
+    }
+  }
+
+  @Override
+  public void onDisconnect() throws Exception {
+    // Forward the disconnection to each plugin.
+    for (FlipperPlugin plugin : plugins) {
+      plugin.onDisconnect();
+    }
+  }
+
+  @Override
+  public boolean runInBackground() {
+    // Check if any of the plugins need to run in the background.
+    for (FlipperPlugin plugin : plugins) {
+      if (plugin.runInBackground()) {
+        return true;
+      }
+    }
+    return false;
+  }
+}