Use proto 0.8.0 and remove extra loadExternalConverters()

Author: karenyrx

modules/transport-grpc/spi/build.gradle

@@ -16,7 +16,7 @@ base {
 
 dependencies {
   api project(":server")
-  api "org.opensearch:protobufs:0.6.0"
+  api "org.opensearch:protobufs:0.8.0"
 }
 
 // no tests...yet?

modules/transport-grpc/spi/src/main/java/org/opensearch/transport/grpc/proto/request/search/query/QueryBuilderProtoConverterSpiRegistry.java

@@ -15,9 +15,7 @@
 import org.opensearch.protobufs.QueryContainer;
 
 import java.util.HashMap;
-import java.util.Iterator;
 import java.util.Map;
-import java.util.ServiceLoader;
 
 /**
  * Registry for QueryBuilderProtoConverter implementations.
@@ -30,38 +28,16 @@ public class QueryBuilderProtoConverterSpiRegistry {
     private final Map<QueryContainer.QueryContainerCase, QueryBuilderProtoConverter> converterMap = new HashMap<>();
 
     /**
-     * Creates a new registry and loads all available converters.
+     * Creates a new registry. External converters will be registered
+     * via the OpenSearch ExtensiblePlugin mechanism.
      */
     @Inject
     public QueryBuilderProtoConverterSpiRegistry() {
-        // Discover converters from plugins using Java's ServiceLoader
-        loadExternalConverters();
+        // External converters are loaded via OpenSearch's ExtensiblePlugin mechanism
+        // and registered manually via registerConverter() calls
     }
 
-    /**
-     * Loads external converters using Java's ServiceLoader mechanism.
-     * Protected for testing purposes.
-     */
-    protected void loadExternalConverters() {
-        ServiceLoader<QueryBuilderProtoConverter> serviceLoader = ServiceLoader.load(QueryBuilderProtoConverter.class);
-        Iterator<QueryBuilderProtoConverter> iterator = serviceLoader.iterator();
-
-        int count = 0;
-        int failedCount = 0;
-        while (iterator.hasNext()) {
-            try {
-                QueryBuilderProtoConverter converter = iterator.next();
-                registerConverter(converter);
-                count++;
-                logger.info("Loaded external query converter for {}: {}", converter.getHandledQueryCase(), converter.getClass().getName());
-            } catch (Exception e) {
-                failedCount++;
-                logger.error("Failed to load external query converter", e);
-            }
-        }
 
-        logger.info("Loaded {} external query converters ({} failed)", count, failedCount);
-    }
 
     /**
      * Converts a protobuf query container to an OpenSearch QueryBuilder.