[Refactor] XContentFactory contentType introspection to MediaTypeParserRegistry (opensearch-project#8826)

XContentFactory is tightly coupled to concrete XContentType. This commit
builds on the MediaType abstractions, specifically
MediaTypeParserRegistry, to decouple contentType introspection (e.g.,
determining type from byte streams) from concrete XContentTypes. This
enables downstream extensions (e.g., serverless or cloud native
implementations) to register their own custom XContentType and define
the serialization format for proper content introspection. This also
removes the tight coupling of :libs:opensearch-x-content with abstract
interface contracts further enabling modularity.

Signed-off-by: Nicholas Walter Knize <nknize@apache.org>

Author: nknize

client/rest-high-level/src/main/java/org/opensearch/client/indices/CreateIndexRequest.java

@@ -187,7 +187,7 @@ public CreateIndexRequest mapping(XContentBuilder source) {
      */
     public CreateIndexRequest mapping(Map<String, ?> source) {
         try {
-            XContentBuilder builder = XContentFactory.contentBuilder(MediaTypeRegistry.getDefaultMediaType());
+            XContentBuilder builder = MediaTypeRegistry.contentBuilder(MediaTypeRegistry.getDefaultMediaType());
             builder.map(source);
             return mapping(BytesReference.bytes(builder), builder.contentType());
         } catch (IOException e) {

client/rest-high-level/src/main/java/org/opensearch/client/indices/PutIndexTemplateRequest.java

@@ -48,6 +48,7 @@
 import org.opensearch.common.xcontent.json.JsonXContent;
 import org.opensearch.common.xcontent.support.XContentMapValues;
 import org.opensearch.core.xcontent.DeprecationHandler;
+import org.opensearch.core.xcontent.MediaTypeRegistry;
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.core.xcontent.ToXContentFragment;
 import org.opensearch.core.xcontent.XContentBuilder;
@@ -267,7 +268,7 @@ public PutIndexTemplateRequest mapping(Map<String, Object> source) {
 
     private PutIndexTemplateRequest internalMapping(Map<String, Object> source) {
         try {
-            XContentBuilder builder = XContentFactory.contentBuilder(XContentType.JSON);
+            XContentBuilder builder = MediaTypeRegistry.contentBuilder(XContentType.JSON);
             builder.map(source);
             MediaType mediaType = builder.contentType();
             Objects.requireNonNull(mediaType);

client/rest-high-level/src/main/java/org/opensearch/client/indices/PutMappingRequest.java

@@ -38,7 +38,6 @@
 import org.opensearch.client.TimedRequest;
 import org.opensearch.core.common.bytes.BytesArray;
 import org.opensearch.core.common.bytes.BytesReference;
-import org.opensearch.common.xcontent.XContentFactory;
 import org.opensearch.core.xcontent.MediaType;
 import org.opensearch.core.xcontent.MediaTypeRegistry;
 import org.opensearch.core.xcontent.ToXContent;
@@ -111,7 +110,7 @@ public MediaType mediaType() {
      */
     public PutMappingRequest source(Map<String, ?> mappingSource) {
         try {
-            XContentBuilder builder = XContentFactory.contentBuilder(MediaTypeRegistry.getDefaultMediaType());
+            XContentBuilder builder = MediaTypeRegistry.contentBuilder(MediaTypeRegistry.getDefaultMediaType());
             builder.map(mappingSource);
             return source(builder);
         } catch (IOException e) {

client/rest-high-level/src/test/java/org/opensearch/client/AbstractRequestTestCase.java

@@ -36,7 +36,6 @@
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.core.xcontent.ToXContent;
 import org.opensearch.core.xcontent.XContent;
-import org.opensearch.common.xcontent.XContentFactory;
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.common.xcontent.XContentType;
 import org.opensearch.test.OpenSearchTestCase;
@@ -60,7 +59,7 @@ public final void testFromXContent() throws IOException {
         final XContentType xContentType = randomFrom(XContentType.values());
         final BytesReference bytes = toShuffledXContent(clientTestInstance, xContentType, ToXContent.EMPTY_PARAMS, randomBoolean());
 
-        final XContent xContent = XContentFactory.xContent(xContentType);
+        final XContent xContent = xContentType.xContent();
         final XContentParser parser = xContent.createParser(xContentRegistry(), LoggingDeprecationHandler.INSTANCE, bytes.streamInput());
         final S serverInstance = doParseToServerInstance(parser);
         assertInstances(serverInstance, clientTestInstance);

client/rest-high-level/src/test/java/org/opensearch/client/AbstractResponseTestCase.java

@@ -36,7 +36,6 @@
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.core.xcontent.ToXContent;
 import org.opensearch.core.xcontent.XContent;
-import org.opensearch.common.xcontent.XContentFactory;
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.common.xcontent.XContentType;
 import org.opensearch.test.OpenSearchTestCase;
@@ -59,7 +58,7 @@ public final void testFromXContent() throws IOException {
         final S serverTestInstance = createServerTestInstance(xContentType);
         final BytesReference bytes = toShuffledXContent(serverTestInstance, xContentType, getParams(), randomBoolean());
 
-        final XContent xContent = XContentFactory.xContent(xContentType);
+        final XContent xContent = xContentType.xContent();
         final XContentParser parser = xContent.createParser(
             NamedXContentRegistry.EMPTY,
             LoggingDeprecationHandler.INSTANCE,

client/rest-high-level/src/test/java/org/opensearch/client/core/GetSourceResponseTests.java

@@ -35,9 +35,9 @@
 import org.opensearch.client.AbstractResponseTestCase;
 import org.opensearch.core.common.bytes.BytesArray;
 import org.opensearch.core.common.bytes.BytesReference;
+import org.opensearch.core.xcontent.MediaTypeRegistry;
 import org.opensearch.core.xcontent.ToXContentObject;
 import org.opensearch.core.xcontent.XContentBuilder;
-import org.opensearch.common.xcontent.XContentHelper;
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.common.xcontent.XContentType;
 
@@ -61,7 +61,7 @@ static class SourceOnlyResponse implements ToXContentObject {
         public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
             // this implementation copied from RestGetSourceAction.RestGetSourceResponseListener::buildResponse
             try (InputStream stream = source.streamInput()) {
-                builder.rawValue(stream, XContentHelper.xContentType(source));
+                builder.rawValue(stream, MediaTypeRegistry.xContentType(source));
             }
             return builder;
         }

client/rest-high-level/src/test/java/org/opensearch/client/indices/CloseIndexResponseTests.java

@@ -39,7 +39,6 @@
 import org.opensearch.common.xcontent.LoggingDeprecationHandler;
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.core.xcontent.XContent;
-import org.opensearch.common.xcontent.XContentFactory;
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.common.xcontent.XContentType;
 import org.opensearch.core.index.Index;
@@ -194,7 +193,7 @@ public final void testBwcFromXContent() throws IOException {
 
             final XContentType xContentType = randomFrom(XContentType.values());
             final BytesReference bytes = toShuffledXContent(expected, xContentType, getParams(), randomBoolean());
-            final XContent xContent = XContentFactory.xContent(xContentType);
+            final XContent xContent = xContentType.xContent();
             final XContentParser parser = xContent.createParser(
                 NamedXContentRegistry.EMPTY,
                 LoggingDeprecationHandler.INSTANCE,
@@ -215,7 +214,7 @@ public final void testBwcFromXContent() throws IOException {
 
             final XContentType xContentType = randomFrom(XContentType.values());
             final BytesReference bytes = toShuffledXContent(expected, xContentType, getParams(), randomBoolean());
-            final XContent xContent = XContentFactory.xContent(xContentType);
+            final XContent xContent = xContentType.xContent();
             final XContentParser parser = xContent.createParser(
                 NamedXContentRegistry.EMPTY,
                 LoggingDeprecationHandler.INSTANCE,

client/rest-high-level/src/test/java/org/opensearch/client/indices/GetIndexTemplatesResponseTests.java

@@ -39,10 +39,10 @@
 import org.opensearch.common.compress.CompressedXContent;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.core.xcontent.DeprecationHandler;
+import org.opensearch.core.xcontent.MediaTypeRegistry;
 import org.opensearch.core.xcontent.NamedXContentRegistry;
 import org.opensearch.core.xcontent.ToXContent;
 import org.opensearch.core.xcontent.XContentBuilder;
-import org.opensearch.common.xcontent.XContentFactory;
 import org.opensearch.common.xcontent.XContentHelper;
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.common.xcontent.XContentType;
@@ -262,7 +262,7 @@ private static AliasMetadata randomAliasMetadata(String name) {
     }
 
     static XContentBuilder randomMapping(String type, XContentType xContentType) throws IOException {
-        XContentBuilder builder = XContentFactory.contentBuilder(xContentType);
+        XContentBuilder builder = MediaTypeRegistry.contentBuilder(xContentType);
         builder.startObject().startObject(type);
 
         randomMappingFields(builder, true);

libs/core/src/main/java/org/opensearch/core/xcontent/MediaType.java

@@ -34,6 +34,8 @@
 
 import org.opensearch.core.common.io.stream.Writeable;
 
+import java.io.IOException;
+import java.io.OutputStream;
 import java.util.Locale;
 
 /**
@@ -69,12 +71,20 @@ default String typeWithSubtype() {
 
     XContent xContent();
 
+    boolean detectedXContent(final byte[] bytes, int offset, int length);
+
+    boolean detectedXContent(final CharSequence content, final int length);
+
     default String mediaType() {
         return mediaTypeWithoutParameters();
     }
 
     String mediaTypeWithoutParameters();
 
+    XContentBuilder contentBuilder() throws IOException;
+
+    XContentBuilder contentBuilder(final OutputStream os) throws IOException;
+
     /**
      * Accepts a format string, which is most of the time is equivalent to {@link MediaType#subtype()}
      * and attempts to match the value to an {@link MediaType}.