=all #13783 replace protobuf dependency by embedded version

- created new subproject akka-protobuf (and added COPYING and LICENSE)
- renamed com.google.protobuf -> akka.protobuf everywhere
- also added such renaming step to the results of protoc compilation in
  project/Protobuf.scala
- had to include transcriptions of Netty’s ProtobufEncoder/Decoder to
  make multi-node-testkit compile again

akka-protobuf/src/main/java/akka/protobuf/ExtensionRegistryLite.java

@@ -0,0 +1,185 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package akka.protobuf;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Equivalent to {@link ExtensionRegistry} but supports only "lite" types.
+ * <p>
+ * If all of your types are lite types, then you only need to use
+ * {@code ExtensionRegistryLite}.  Similarly, if all your types are regular
+ * types, then you only need {@link ExtensionRegistry}.  Typically it does not
+ * make sense to mix the two, since if you have any regular types in your
+ * program, you then require the full runtime and lose all the benefits of
+ * the lite runtime, so you might as well make all your types be regular types.
+ * However, in some cases (e.g. when depending on multiple third-party libraries
+ * where one uses lite types and one uses regular), you may find yourself
+ * wanting to mix the two.  In this case things get more complicated.
+ * <p>
+ * There are three factors to consider:  Whether the type being extended is
+ * lite, whether the embedded type (in the case of a message-typed extension)
+ * is lite, and whether the extension itself is lite.  Since all three are
+ * declared in different files, they could all be different.  Here are all
+ * the combinations and which type of registry to use:
+ * <pre>
+ *   Extended type     Inner type    Extension         Use registry
+ *   =======================================================================
+ *   lite              lite          lite              ExtensionRegistryLite
+ *   lite              regular       lite              ExtensionRegistry
+ *   regular           regular       regular           ExtensionRegistry
+ *   all other combinations                            not supported
+ * </pre>
+ * <p>
+ * Note that just as regular types are not allowed to contain lite-type fields,
+ * they are also not allowed to contain lite-type extensions.  This is because
+ * regular types must be fully accessible via reflection, which in turn means
+ * that all the inner messages must also support reflection.  On the other hand,
+ * since regular types implement the entire lite interface, there is no problem
+ * with embedding regular types inside lite types.
+ *
+ * @author kenton@google.com Kenton Varda
+ */
+public class ExtensionRegistryLite {
+
+  // Set true to enable lazy parsing feature for MessageSet.
+  //
+  // TODO(xiangl): Now we use a global flag to control whether enable lazy
+  // parsing feature for MessageSet, which may be too crude for some
+  // applications. Need to support this feature on smaller granularity.
+  private static volatile boolean eagerlyParseMessageSets = false;
+
+  public static boolean isEagerlyParseMessageSets() {
+    return eagerlyParseMessageSets;
+  }
+
+  public static void setEagerlyParseMessageSets(boolean isEagerlyParse) {
+    eagerlyParseMessageSets = isEagerlyParse;
+  }
+
+  /** Construct a new, empty instance. */
+  public static ExtensionRegistryLite newInstance() {
+    return new ExtensionRegistryLite();
+  }
+
+  /** Get the unmodifiable singleton empty instance. */
+  public static ExtensionRegistryLite getEmptyRegistry() {
+    return EMPTY;
+  }
+
+  /** Returns an unmodifiable view of the registry. */
+  public ExtensionRegistryLite getUnmodifiable() {
+    return new ExtensionRegistryLite(this);
+  }
+
+  /**
+   * Find an extension by containing type and field number.
+   *
+   * @return Information about the extension if found, or {@code null}
+   *         otherwise.
+   */
+  @SuppressWarnings("unchecked")
+  public <ContainingType extends MessageLite>
+      GeneratedMessageLite.GeneratedExtension<ContainingType, ?>
+        findLiteExtensionByNumber(
+          final ContainingType containingTypeDefaultInstance,
+          final int fieldNumber) {
+    return (GeneratedMessageLite.GeneratedExtension<ContainingType, ?>)
+      extensionsByNumber.get(
+        new ObjectIntPair(containingTypeDefaultInstance, fieldNumber));
+  }
+
+  /** Add an extension from a lite generated file to the registry. */
+  public final void add(
+      final GeneratedMessageLite.GeneratedExtension<?, ?> extension) {
+    extensionsByNumber.put(
+      new ObjectIntPair(extension.getContainingTypeDefaultInstance(),
+                        extension.getNumber()),
+      extension);
+  }
+
+  // =================================================================
+  // Private stuff.
+
+  // Constructors are package-private so that ExtensionRegistry can subclass
+  // this.
+
+  ExtensionRegistryLite() {
+    this.extensionsByNumber =
+        new HashMap<ObjectIntPair,
+                    GeneratedMessageLite.GeneratedExtension<?, ?>>();
+  }
+
+  ExtensionRegistryLite(ExtensionRegistryLite other) {
+    if (other == EMPTY) {
+      this.extensionsByNumber = Collections.emptyMap();
+    } else {
+      this.extensionsByNumber =
+        Collections.unmodifiableMap(other.extensionsByNumber);
+    }
+  }
+
+  private final Map<ObjectIntPair,
+                    GeneratedMessageLite.GeneratedExtension<?, ?>>
+      extensionsByNumber;
+
+  private ExtensionRegistryLite(boolean empty) {
+    this.extensionsByNumber = Collections.emptyMap();
+  }
+  private static final ExtensionRegistryLite EMPTY =
+    new ExtensionRegistryLite(true);
+
+  /** A (Object, int) pair, used as a map key. */
+  private static final class ObjectIntPair {
+    private final Object object;
+    private final int number;
+
+    ObjectIntPair(final Object object, final int number) {
+      this.object = object;
+      this.number = number;
+    }
+
+    @Override
+    public int hashCode() {
+      return System.identityHashCode(object) * ((1 << 16) - 1) + number;
+    }
+    @Override
+    public boolean equals(final Object obj) {
+      if (!(obj instanceof ObjectIntPair)) {
+        return false;
+      }
+      final ObjectIntPair other = (ObjectIntPair)obj;
+      return object == other.object && number == other.number;
+    }
+  }
+}