Improved code comments

Author: quux00

server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java

@@ -554,6 +554,11 @@ public final void validate(MappingLookup mappers) {
         }
     }
 
+    /**
+     * This method is separated out to allow subclasses (such as RootObjectMapper) to
+     * override it and add in additional validations beyond what the mapper.validate()
+     * method will check on each mapping.
+     */
     protected void validateSubField(Mapper mapper, MappingLookup mappers) {
         mapper.validate(mappers);
     }

server/src/main/java/org/elasticsearch/index/mapper/RootObjectMapper.java

@@ -554,6 +554,10 @@ public int getTotalFieldsCount() {
         return super.getTotalFieldsCount() - 1 + runtimeFields.size();
     }
 
+    /**
+     * Overrides in order to run the namespace validator first and then delegates to the
+     * standard validateSubField on the parent class
+     */
     @Override
     protected void validateSubField(Mapper mapper, MappingLookup mappers) {
         namespaceValidator.validateNamespace(subobjects(), mapper.leafName());

server/src/main/java/org/elasticsearch/node/NodeConstruction.java

@@ -697,7 +697,6 @@ private void construct(
 
         modules.bindToInstance(Tracer.class, telemetryProvider.getTracer());
 
-        // serverless deployments plug-in the namespace validator that prohibits mappings with "_project"
         RootObjectMapperNamespaceValidator namespaceValidator = pluginsService.loadSingletonServiceProvider(
             RootObjectMapperNamespaceValidator.class,
             () -> new DefaultRootObjectMapperNamespaceValidator()