Make root field transient in all classes

src/main/java/org/kohsuke/github/GitHub.java

@@ -1208,26 +1208,34 @@ public Reader renderMarkdown(String text) throws IOException {
     }
 
     /**
-     * Do not use this method. This method will be removed and should never have been needed in the first place.
+     * Gets an {@link ObjectWriter} that can be used to convert data objects in this library to JSON.
+     *
+     * If you must convert data object in this library to JSON, the {@link ObjectWriter} returned by this method is the
+     * only support way of doing so. This {@link ObjectWriter} can be used to convert any library data object to JSON
+     * without throwing an exception.
+     *
+     * WARNING: While the JSON generated is generally expected to be stable, it is not part of the API of this library
+     * and may change without warning. Use with extreme caution.
      *
      * @return an {@link ObjectWriter} instance that can be further configured.
-     * @deprecated DO NOT USE THIS METHOD. Provided for backward compatibility with projects that did their own jackson
-     *             mapping of this project's data objects, such as Jenkins Blue Ocean.
      */
-    @Deprecated
     @Nonnull
     public static ObjectWriter getMappingObjectWriter() {
         return GitHubClient.getMappingObjectWriter();
     }
 
     /**
-     * Do not use this method. This method will be removed and should never have been needed in the first place.
+     * Gets an {@link ObjectReader} that can be used to convert JSON into library data objects.
+     *
+     * If you must manually create library data objects from JSON, the {@link ObjectReader} returned by this method is
+     * the only supported way of doing so.
+     *
+     * WARNING: Objects generated from this method have limited functionality. They will not throw when being crated
+     * from valid JSON matching the expected object, but they are not guaranteed to be usable beyond that. Use with
+     * extreme caution.
      *
      * @return an {@link ObjectReader} instance that can be further configured.
-     * @deprecated DO NOT USE THIS METHOD. Provided for backward compatibility with projects that did their own jackson
-     *             mapping of this project's data objects, such as Jenkins Blue Ocean.
      */
-    @Deprecated
     @Nonnull
     public static ObjectReader getMappingObjectReader() {
         return GitHubClient.getMappingObjectReader(GitHub.offline());

src/test/java/org/kohsuke/github/GitHubStaticTest.java

@@ -240,6 +240,12 @@ public void testMappingReaderWriter() throws Exception {
         assertThat(readRepo.root, nullValue());
         assertThat(readRepo.getResponseHeaderFields(), nullValue());
 
+        readRepo = GitHub.getMappingObjectReader().forType(GHRepository.class).readValue(repoString);
+
+        // This should never happen if the internal method isn't used
+        assertThat(readRepo.root.getConnector(), equalTo(HttpConnector.OFFLINE));
+        assertThat(readRepo.getResponseHeaderFields(), nullValue());
+
         String readRepoString = GitHub.getMappingObjectWriter().writeValueAsString(readRepo);
         assertThat(readRepoString, equalTo(repoString));