Add superclasses for gson-jackson migration

Added common classes needed by other gson-jackson code.
Modified some logic to make it more maintainable or perform better.
Updated comments and spacing.
Fix another comment.
Moved gson classes from utils to a separate gson project.
Added GsonXxx annotations to mirror jackson annotations.
Removed unneeded dependencies from gson pom.
Removed old GsonMessage class from policy-endpoints.
Removed trailing spaces.
Updated licenses.
Removed more trailing spaces.
Removed unneeded checkstyle suppression file from utils.

Change-Id: I1a285500faeb0a0b6a1467d09b92ecd3cded713e
Issue-ID: POLICY-1428
Signed-off-by: Jim Hahn <jrh3@att.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/gson/src/main/java/org/onap/policy/common/gson/internal/Deserializer.java b/gson/src/main/java/org/onap/policy/common/gson/internal/Deserializer.java
new file mode 100644
index 00000000..f2975860
--- /dev/null
+++ b/gson/src/main/java/org/onap/policy/common/gson/internal/Deserializer.java
@@ -0,0 +1,39 @@
+/*
+ * ============LICENSE_START=======================================================
+ * ONAP
+ * ================================================================================
+ * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
+ * ================================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ============LICENSE_END=========================================================
+ */
+
+package org.onap.policy.common.gson.internal;
+
+import com.google.gson.JsonObject;
+
+/**
+ * Super class of all de-serializers.
+ */
+public interface Deserializer {
+
+    String INVOKE_ERR = "cannot invoke method to deserialize: ";
+
+    /**
+     * Gets an value from a tree, converts it, and puts it into a target object.
+     *
+     * @param source tree from which to get the value
+     * @param target where to place the converted value
+     */
+    void getFromTree(JsonObject source, Object target);
+}