jackson ObjectMapper: auto-detect modules

jackson 2.x still supports java 7 and thus does not automatically
support java 8 classes. this will change with jackson 3.x (see e.g.
this [PR adding JSR310 date support] to 3.x).

PR #251 added documentation on how a custom `ObjectMapper` can be
registered - but there's no reason why we can't just enable
auto-detection centrally. the docs mention that performance should be
considered, but this is IMHO not relevant here since we only construct
it once and then keep the same `ObjectMapper` (which in turn the docs
mention as best practices).

Signed-off-by: Ralph Ursprung <Ralph.Ursprung@avaloq.com>

[PR adding JSR310 date support]: FasterXML/jackson-databind#5032

Author: rursprung

CHANGELOG.md

@@ -4,6 +4,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ## [Unreleased 3.x]
 ### Added
 - Added support for Index Management plugin APIs ([#1604](https://github.com/opensearch-project/opensearch-java/pull/1604))
+- Jackson `ObjectMapper` modules are now being auto-detected ([#1614](https://github.com/opensearch-project/opensearch-java/pull/1614))
 
 ### Dependencies
 - Bump `org.owasp.dependencycheck` from 12.1.1 to 12.1.2 ([#1608](https://github.com/opensearch-project/opensearch-java/pull/1608), [#1607](https://github.com/opensearch-project/opensearch-java/pull/1607))

USER_GUIDE.md

@@ -99,13 +99,7 @@ OpenSearchTransport transport = new RestClientTransport(restClient, new JacksonJ
 OpenSearchClient client = new OpenSearchClient(transport);
 ```
 
-The `JacksonJsonpMapper` class (2.x versions) only supports Java 7 objects by default. [Java 8 modules](https://github.com/FasterXML/jackson-modules-java8) to support JDK8 classes such as the Date and Time API (JSR-310), `Optional`, and more can be used by including [the additional datatype dependency](https://github.com/FasterXML/jackson-modules-java8#usage) and adding the module.  For example, to include JSR-310 classes:
-
-```java
-OpenSearchTransport transport = new RestClientTransport(restClient,
-    new JacksonJsonpMapper(new ObjectMapper().registerModule(new JavaTimeModule()))); 
-OpenSearchClient client = new OpenSearchClient(transport);
-```
+The `JacksonJsonpMapper` class (2.x versions) only supports Java 7 objects by default. [Java 8 modules](https://github.com/FasterXML/jackson-modules-java8) to support JDK8 classes such as the Date and Time API (JSR-310), `Optional`, and more can be used by including [the additional datatype dependency](https://github.com/FasterXML/jackson-modules-java8#usage) and adding the module. Auto-detection for these modules is enabled, adding them to the classpath is enough.
 
 Upcoming OpenSearch `3.0.0` release brings HTTP/2 support and as such, the `RestClientTransport` would switch to HTTP/2 if available (for both HTTPS and/or HTTP protocols). The desired protocol could be forced using `RestClientBuilder.HttpClientConfigCallback`.
 

java-client/src/main/java/org/opensearch/client/json/jackson/JacksonJsonpMapper.java

@@ -63,7 +63,9 @@ public JacksonJsonpMapper(ObjectMapper objectMapper, JsonFactory jsonFactory) {
 
     public JacksonJsonpMapper() {
         this(
-            new ObjectMapper().configure(SerializationFeature.INDENT_OUTPUT, false).setSerializationInclusion(JsonInclude.Include.NON_NULL)
+            new ObjectMapper().configure(SerializationFeature.INDENT_OUTPUT, false)
+                .setSerializationInclusion(JsonInclude.Include.NON_NULL)
+                .findAndRegisterModules()
         );
     }