[Backport 2.x] Clean up miscellaneous code smells, eliminate most Guava use (#327)

src/main/java/org/opensearch/flowframework/FlowFrameworkPlugin.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework;
 
-import com.google.common.collect.ImmutableList;
 import org.opensearch.action.ActionRequest;
 import org.opensearch.client.Client;
 import org.opensearch.cluster.metadata.IndexNameExpressionResolver;
@@ -127,7 +126,7 @@ public Collection<Object> createComponents(
             settings
         );
 
-        return ImmutableList.of(workflowStepFactory, workflowProcessSorter, encryptorUtils, flowFrameworkIndicesHandler);
+        return List.of(workflowStepFactory, workflowProcessSorter, encryptorUtils, flowFrameworkIndicesHandler);
     }
 
     @Override
@@ -140,7 +139,7 @@ public List<RestHandler> getRestHandlers(
         IndexNameExpressionResolver indexNameExpressionResolver,
         Supplier<DiscoveryNodes> nodesInCluster
     ) {
-        return ImmutableList.of(
+        return List.of(
             new RestCreateWorkflowAction(flowFrameworkFeatureEnabledSetting, settings, clusterService),
             new RestDeleteWorkflowAction(flowFrameworkFeatureEnabledSetting),
             new RestProvisionWorkflowAction(flowFrameworkFeatureEnabledSetting),
@@ -154,7 +153,7 @@ public List<RestHandler> getRestHandlers(
 
     @Override
     public List<ActionHandler<? extends ActionRequest, ? extends ActionResponse>> getActions() {
-        return ImmutableList.of(
+        return List.of(
             new ActionHandler<>(CreateWorkflowAction.INSTANCE, CreateWorkflowTransportAction.class),
             new ActionHandler<>(DeleteWorkflowAction.INSTANCE, DeleteWorkflowTransportAction.class),
             new ActionHandler<>(ProvisionWorkflowAction.INSTANCE, ProvisionWorkflowTransportAction.class),
@@ -168,20 +167,13 @@ public List<RestHandler> getRestHandlers(
 
     @Override
     public List<Setting<?>> getSettings() {
-        List<Setting<?>> settings = ImmutableList.of(
-            FLOW_FRAMEWORK_ENABLED,
-            MAX_WORKFLOWS,
-            MAX_WORKFLOW_STEPS,
-            WORKFLOW_REQUEST_TIMEOUT,
-            MAX_GET_TASK_REQUEST_RETRY
-        );
-        return settings;
+        return List.of(FLOW_FRAMEWORK_ENABLED, MAX_WORKFLOWS, MAX_WORKFLOW_STEPS, WORKFLOW_REQUEST_TIMEOUT, MAX_GET_TASK_REQUEST_RETRY);
     }
 
     @Override
     public List<ExecutorBuilder<?>> getExecutorBuilders(Settings settings) {
         // TODO : Determine final size/queueSize values for the provision thread pool
-        return ImmutableList.of(
+        return List.of(
             new FixedExecutorBuilder(
                 settings,
                 PROVISION_THREAD_POOL,

src/main/java/org/opensearch/flowframework/common/WorkflowResources.java

@@ -91,7 +91,7 @@ public static String getResourceByWorkflowStep(String workflowStep) throws FlowF
                 }
             }
         }
-        logger.error("Unable to find resource type for step: " + workflowStep);
+        logger.error("Unable to find resource type for step: {}", workflowStep);
         throw new FlowFrameworkException("Unable to find resource type for step: " + workflowStep, RestStatus.BAD_REQUEST);
     }
 
@@ -109,7 +109,7 @@ public static String getDeprovisionStepByWorkflowStep(String workflowStep) throw
                 }
             }
         }
-        logger.error("Unable to find deprovision step for step: " + workflowStep);
+        logger.error("Unable to find deprovision step for step: {}", workflowStep);
         throw new FlowFrameworkException("Unable to find deprovision step for step: " + workflowStep, RestStatus.BAD_REQUEST);
     }
 

src/main/java/org/opensearch/flowframework/indices/FlowFrameworkIndicesHandler.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.indices;
 
-import com.google.common.base.Charsets;
 import com.google.common.io.Resources;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -32,7 +31,6 @@
 import org.opensearch.core.action.ActionListener;
 import org.opensearch.core.rest.RestStatus;
 import org.opensearch.core.xcontent.ToXContent;
-import org.opensearch.core.xcontent.ToXContentObject;
 import org.opensearch.core.xcontent.XContentBuilder;
 import org.opensearch.flowframework.common.WorkflowResources;
 import org.opensearch.flowframework.exception.FlowFrameworkException;
@@ -47,6 +45,7 @@
 
 import java.io.IOException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
@@ -165,7 +164,7 @@ public void initFlowFrameworkIndexIfAbsent(FlowFrameworkIndex index, ActionListe
         String mapping = index.getMapping();
 
         try (ThreadContext.StoredContext threadContext = client.threadPool().getThreadContext().stashContext()) {
-            ActionListener<Boolean> internalListener = ActionListener.runBefore(listener, () -> threadContext.restore());
+            ActionListener<Boolean> internalListener = ActionListener.runBefore(listener, threadContext::restore);
             if (!clusterService.state().metadata().hasIndex(indexName)) {
                 @SuppressWarnings("deprecation")
                 ActionListener<CreateIndexResponse> actionListener = ActionListener.wrap(r -> {
@@ -176,7 +175,7 @@ public void initFlowFrameworkIndexIfAbsent(FlowFrameworkIndex index, ActionListe
                         internalListener.onResponse(false);
                     }
                 }, e -> {
-                    logger.error("Failed to create index " + indexName, e);
+                    logger.error("Failed to create index {}", indexName, e);
                     internalListener.onFailure(new FlowFrameworkException(e.getMessage(), ExceptionsHelper.status(e)));
                 });
                 CreateIndexRequest request = new CreateIndexRequest(indexName).mapping(mapping).settings(indexSettings);
@@ -274,7 +273,7 @@ private void shouldUpdateIndex(String indexName, Integer newVersion, ActionListe
         Integer oldVersion = NO_SCHEMA_VERSION;
         Map<String, Object> indexMapping = indexMetaData.mapping().getSourceAsMap();
         Object meta = indexMapping.get(META);
-        if (meta != null && meta instanceof Map) {
+        if (meta instanceof Map) {
             @SuppressWarnings("unchecked")
             Map<String, Object> metaMapping = (Map<String, Object>) meta;
             Object schemaVersion = metaMapping.get(SCHEMA_VERSION_FIELD);
@@ -294,7 +293,7 @@ private void shouldUpdateIndex(String indexName, Integer newVersion, ActionListe
      */
     public static String getIndexMappings(String mapping) throws IOException {
         URL url = FlowFrameworkIndicesHandler.class.getClassLoader().getResource(mapping);
-        return Resources.toString(url, Charsets.UTF_8);
+        return Resources.toString(url, StandardCharsets.UTF_8);
     }
 
     /**
@@ -316,7 +315,7 @@ public void putTemplateToGlobalContext(Template template, ActionListener<IndexRe
                 Template templateWithEncryptedCredentials = encryptorUtils.encryptTemplateCredentials(template);
                 request.source(templateWithEncryptedCredentials.toXContent(builder, ToXContent.EMPTY_PARAMS))
                     .setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
-                client.index(request, ActionListener.runBefore(listener, () -> context.restore()));
+                client.index(request, ActionListener.runBefore(listener, context::restore));
             } catch (Exception e) {
                 String errorMessage = "Failed to index global_context index";
                 logger.error(errorMessage);
@@ -372,7 +371,7 @@ public void putInitialStateToWorkflowState(String workflowId, User user, ActionL
             ) {
                 request.source(state.toXContent(builder, ToXContent.EMPTY_PARAMS)).setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
                 request.id(workflowId);
-                client.index(request, ActionListener.runBefore(listener, () -> context.restore()));
+                client.index(request, ActionListener.runBefore(listener, context::restore));
             } catch (Exception e) {
                 String errorMessage = "Failed to put state index document";
                 logger.error(errorMessage, e);
@@ -408,7 +407,7 @@ public void updateTemplateInGlobalContext(String documentId, Template template,
                 Template encryptedTemplate = encryptorUtils.encryptTemplateCredentials(template);
                 request.source(encryptedTemplate.toXContent(builder, ToXContent.EMPTY_PARAMS))
                     .setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
-                client.index(request, ActionListener.runBefore(listener, () -> context.restore()));
+                client.index(request, ActionListener.runBefore(listener, context::restore));
             } catch (Exception e) {
                 String errorMessage = "Failed to update global_context entry : " + documentId;
                 logger.error(errorMessage, e);
@@ -441,7 +440,7 @@ public void updateFlowFrameworkSystemIndexDoc(
                 updateRequest.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
                 updateRequest.retryOnConflict(3);
                 // TODO: decide what condition can be considered as an update conflict and add retry strategy
-                client.update(updateRequest, ActionListener.runBefore(listener, () -> context.restore()));
+                client.update(updateRequest, ActionListener.runBefore(listener, context::restore));
             } catch (Exception e) {
                 String errorMessage = "Failed to update " + WORKFLOW_STATE_INDEX + " entry : " + documentId;
                 logger.error(errorMessage, e);
@@ -475,7 +474,7 @@ public void updateFlowFrameworkSystemIndexDocWithScript(
                 updateRequest.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
                 updateRequest.retryOnConflict(3);
                 // TODO: Implement our own concurrency control to improve on retry mechanism
-                client.update(updateRequest, ActionListener.runBefore(listener, () -> context.restore()));
+                client.update(updateRequest, ActionListener.runBefore(listener, context::restore));
             } catch (Exception e) {
                 logger.error("Failed to update {} entry : {}. {}", indexName, documentId, e.getMessage());
                 listener.onFailure(
@@ -508,7 +507,7 @@ public void updateResourceInStateIndex(
             resourceId
         );
         XContentBuilder builder = XContentBuilder.builder(XContentType.JSON.xContent());
-        newResource.toXContent(builder, ToXContentObject.EMPTY_PARAMS);
+        newResource.toXContent(builder, ToXContent.EMPTY_PARAMS);
 
         // The script to append a new object to the resources_created array
         Script script = new Script(

src/main/java/org/opensearch/flowframework/model/WorkflowValidator.java

@@ -8,13 +8,13 @@
  */
 package org.opensearch.flowframework.model;
 
-import com.google.common.base.Charsets;
 import com.google.common.io.Resources;
 import org.opensearch.core.xcontent.XContentParser;
 import org.opensearch.flowframework.util.ParseUtils;
 
 import java.io.IOException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -63,7 +63,7 @@ public static WorkflowValidator parse(XContentParser parser) throws IOException
      */
     public static WorkflowValidator parse(String file) throws IOException {
         URL url = WorkflowValidator.class.getClassLoader().getResource(file);
-        String json = Resources.toString(url, Charsets.UTF_8);
+        String json = Resources.toString(url, StandardCharsets.UTF_8);
         return parse(ParseUtils.jsonToParser(json));
     }
 

src/main/java/org/opensearch/flowframework/rest/RestCreateWorkflowAction.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.opensearch.client.node.NodeClient;
@@ -70,7 +69,7 @@ public String getName() {
 
     @Override
     public List<Route> routes() {
-        return ImmutableList.of(
+        return List.of(
             // Create new workflow
             new Route(RestRequest.Method.POST, String.format(Locale.ROOT, "%s", WORKFLOW_URI)),
             // Update use case template

src/main/java/org/opensearch/flowframework/rest/RestDeleteWorkflowAction.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.opensearch.ExceptionsHelper;
@@ -57,7 +56,7 @@ public String getName() {
 
     @Override
     public List<Route> routes() {
-        return ImmutableList.of(new Route(RestRequest.Method.DELETE, String.format(Locale.ROOT, "%s/{%s}", WORKFLOW_URI, WORKFLOW_ID)));
+        return List.of(new Route(RestRequest.Method.DELETE, String.format(Locale.ROOT, "%s/{%s}", WORKFLOW_URI, WORKFLOW_ID)));
     }
 
     @Override

src/main/java/org/opensearch/flowframework/rest/RestDeprovisionWorkflowAction.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.opensearch.ExceptionsHelper;
@@ -101,7 +100,7 @@ protected BaseRestHandler.RestChannelConsumer prepareRequest(RestRequest request
 
     @Override
     public List<Route> routes() {
-        return ImmutableList.of(
+        return List.of(
             new Route(RestRequest.Method.POST, String.format(Locale.ROOT, "%s/{%s}/%s", WORKFLOW_URI, WORKFLOW_ID, "_deprovision"))
         );
     }

src/main/java/org/opensearch/flowframework/rest/RestGetWorkflowAction.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.opensearch.ExceptionsHelper;
@@ -57,7 +56,7 @@ public String getName() {
 
     @Override
     public List<Route> routes() {
-        return ImmutableList.of(new Route(RestRequest.Method.GET, String.format(Locale.ROOT, "%s/{%s}", WORKFLOW_URI, WORKFLOW_ID)));
+        return List.of(new Route(RestRequest.Method.GET, String.format(Locale.ROOT, "%s/{%s}", WORKFLOW_URI, WORKFLOW_ID)));
     }
 
     @Override

src/main/java/org/opensearch/flowframework/rest/RestGetWorkflowStateAction.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.opensearch.ExceptionsHelper;
@@ -104,8 +103,6 @@ protected BaseRestHandler.RestChannelConsumer prepareRequest(RestRequest request
 
     @Override
     public List<Route> routes() {
-        return ImmutableList.of(
-            new Route(RestRequest.Method.GET, String.format(Locale.ROOT, "%s/{%s}/%s", WORKFLOW_URI, WORKFLOW_ID, "_status"))
-        );
+        return List.of(new Route(RestRequest.Method.GET, String.format(Locale.ROOT, "%s/{%s}/%s", WORKFLOW_URI, WORKFLOW_ID, "_status")));
     }
 }

src/main/java/org/opensearch/flowframework/rest/RestProvisionWorkflowAction.java

@@ -8,7 +8,6 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.opensearch.client.node.NodeClient;
@@ -59,7 +58,7 @@ public String getName() {
 
     @Override
     public List<Route> routes() {
-        return ImmutableList.of(
+        return List.of(
             // Provision workflow from indexed use case template
             new Route(RestRequest.Method.POST, String.format(Locale.ROOT, "%s/{%s}/%s", WORKFLOW_URI, WORKFLOW_ID, "_provision"))
         );

src/main/java/org/opensearch/flowframework/rest/RestSearchWorkflowAction.java

@@ -8,11 +8,12 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.opensearch.flowframework.common.FlowFrameworkFeatureEnabledSetting;
 import org.opensearch.flowframework.model.Template;
 import org.opensearch.flowframework.transport.SearchWorkflowAction;
 
+import java.util.List;
+
 import static org.opensearch.flowframework.common.CommonValue.GLOBAL_CONTEXT_INDEX;
 import static org.opensearch.flowframework.common.CommonValue.WORKFLOW_URI;
 
@@ -31,7 +32,7 @@ public class RestSearchWorkflowAction extends AbstractSearchWorkflowAction<Templ
      */
     public RestSearchWorkflowAction(FlowFrameworkFeatureEnabledSetting flowFrameworkFeatureEnabledSetting) {
         super(
-            ImmutableList.of(SEARCH_WORKFLOW_PATH),
+            List.of(SEARCH_WORKFLOW_PATH),
             GLOBAL_CONTEXT_INDEX,
             Template.class,
             SearchWorkflowAction.INSTANCE,

src/main/java/org/opensearch/flowframework/rest/RestSearchWorkflowStateAction.java

@@ -8,11 +8,12 @@
  */
 package org.opensearch.flowframework.rest;
 
-import com.google.common.collect.ImmutableList;
 import org.opensearch.flowframework.common.FlowFrameworkFeatureEnabledSetting;
 import org.opensearch.flowframework.model.WorkflowState;
 import org.opensearch.flowframework.transport.SearchWorkflowStateAction;
 
+import java.util.List;
+
 import static org.opensearch.flowframework.common.CommonValue.WORKFLOW_STATE_INDEX;
 import static org.opensearch.flowframework.common.CommonValue.WORKFLOW_URI;
 
@@ -31,7 +32,7 @@ public class RestSearchWorkflowStateAction extends AbstractSearchWorkflowAction<
      */
     public RestSearchWorkflowStateAction(FlowFrameworkFeatureEnabledSetting flowFrameworkFeatureEnabledSetting) {
         super(
-            ImmutableList.of(SEARCH_WORKFLOW_STATE_PATH),
+            List.of(SEARCH_WORKFLOW_STATE_PATH),
             WORKFLOW_STATE_INDEX,
             WorkflowState.class,
             SearchWorkflowStateAction.INSTANCE,