[SCB-2545] Inner class can be static (#3036)

## changes
- inner class can be static
- fix some javadoc errors
diff --git a/common/common-access-log/src/main/java/org/apache/servicecomb/common/accessLog/core/element/impl/ResponseSizeAccessItem.java b/common/common-access-log/src/main/java/org/apache/servicecomb/common/accessLog/core/element/impl/ResponseSizeAccessItem.java
index 98845b5..bbf094b 100644
--- a/common/common-access-log/src/main/java/org/apache/servicecomb/common/accessLog/core/element/impl/ResponseSizeAccessItem.java
+++ b/common/common-access-log/src/main/java/org/apache/servicecomb/common/accessLog/core/element/impl/ResponseSizeAccessItem.java
@@ -44,9 +44,7 @@
 
   @Override
   public void appendClientFormattedItem(InvocationFinishEvent finishEvent, StringBuilder builder) {
-    /**
-     * client do not know how to calculate is right, maybe Object#toString().length
-     */
+    // client do not know how to calculate is right, maybe Object#toString().length
     builder.append(zeroBytes);
   }
 
diff --git a/common/common-rest/src/test/java/org/apache/servicecomb/common/rest/TestAbstractRestInvocation.java b/common/common-rest/src/test/java/org/apache/servicecomb/common/rest/TestAbstractRestInvocation.java
index d9b3ee4..7ec45e1 100644
--- a/common/common-rest/src/test/java/org/apache/servicecomb/common/rest/TestAbstractRestInvocation.java
+++ b/common/common-rest/src/test/java/org/apache/servicecomb/common/rest/TestAbstractRestInvocation.java
@@ -111,7 +111,7 @@
 
   static RestOperationMeta restOperation;
 
-  class AbstractHttpServletRequestForTest extends AbstractHttpServletRequest {
+  static class AbstractHttpServletRequestForTest extends AbstractHttpServletRequest {
     @Override
     public String getHeader(String name) {
       return null;
diff --git a/core/src/test/java/org/apache/servicecomb/core/transport/TestAbstractTransport.java b/core/src/test/java/org/apache/servicecomb/core/transport/TestAbstractTransport.java
index adea616..b0fd7ba 100644
--- a/core/src/test/java/org/apache/servicecomb/core/transport/TestAbstractTransport.java
+++ b/core/src/test/java/org/apache/servicecomb/core/transport/TestAbstractTransport.java
@@ -47,7 +47,7 @@
     ReflectionUtils.invokeMethod(updatePropertyMethod, null, key, value);
   }
 
-  class MyAbstractTransport extends AbstractTransport {
+  static class MyAbstractTransport extends AbstractTransport {
 
     @Override
     public String getName() {
diff --git a/demo/demo-jaxrs/jaxrs-client/src/main/java/org/apache/servicecomb/demo/jaxrs/client/CustomLoadbalanceExtensionsFactory.java b/demo/demo-jaxrs/jaxrs-client/src/main/java/org/apache/servicecomb/demo/jaxrs/client/CustomLoadbalanceExtensionsFactory.java
index c7c545b..6e1ccf8 100644
--- a/demo/demo-jaxrs/jaxrs-client/src/main/java/org/apache/servicecomb/demo/jaxrs/client/CustomLoadbalanceExtensionsFactory.java
+++ b/demo/demo-jaxrs/jaxrs-client/src/main/java/org/apache/servicecomb/demo/jaxrs/client/CustomLoadbalanceExtensionsFactory.java
@@ -28,11 +28,11 @@
 @Component
 public class CustomLoadbalanceExtensionsFactory implements ExtensionsFactory {
 
-  class MyCustomRule extends RoundRobinRuleExt {
+  static class MyCustomRule extends RoundRobinRuleExt {
 
   }
 
-  class MyCustomHandler extends DefaultLoadBalancerRetryHandler {
+  static class MyCustomHandler extends DefaultLoadBalancerRetryHandler {
     @Override
     public boolean isRetriableException(Throwable e, boolean sameServer) {
       if (retryEnabled) {
diff --git a/foundations/foundation-spi/src/test/java/org/apache/servicecomb/foundation/common/utils/TestSPIServiceUtils.java b/foundations/foundation-spi/src/test/java/org/apache/servicecomb/foundation/common/utils/TestSPIServiceUtils.java
index 3f65a10..040c840 100644
--- a/foundations/foundation-spi/src/test/java/org/apache/servicecomb/foundation/common/utils/TestSPIServiceUtils.java
+++ b/foundations/foundation-spi/src/test/java/org/apache/servicecomb/foundation/common/utils/TestSPIServiceUtils.java
@@ -106,7 +106,7 @@
     int getOrder();
   }
 
-  public class PriorityImpl implements PriorityIntf {
+  public static class PriorityImpl implements PriorityIntf {
     private final String name;
 
     private final int order;
diff --git a/foundations/foundation-ssl/src/test/java/org/apache/servicecomb/foundation/ssl/TrustManagerExtTest.java b/foundations/foundation-ssl/src/test/java/org/apache/servicecomb/foundation/ssl/TrustManagerExtTest.java
index a9a5bce..f4b7d2d 100644
--- a/foundations/foundation-ssl/src/test/java/org/apache/servicecomb/foundation/ssl/TrustManagerExtTest.java
+++ b/foundations/foundation-ssl/src/test/java/org/apache/servicecomb/foundation/ssl/TrustManagerExtTest.java
@@ -53,7 +53,7 @@
 public class TrustManagerExtTest {
   final String strFilePath = Thread.currentThread().getContextClassLoader().getResource("").getPath();
 
-  class MyX509ExtendedTrustManager extends X509ExtendedTrustManager {
+  static class MyX509ExtendedTrustManager extends X509ExtendedTrustManager {
     public void checkClientTrusted(X509Certificate[] paramArrayOfX509Certificate, String paramString,
         Socket paramSocket) throws CertificateException {
     }
@@ -83,7 +83,7 @@
     }
   }
 
-  class MyX509Certificate extends X509Certificate {
+  static class MyX509Certificate extends X509Certificate {
     private static final long serialVersionUID = -3585440601605666276L;
 
     public void checkValidity() throws CertificateExpiredException, CertificateNotYetValidException {
diff --git a/governance/src/main/java/org/apache/servicecomb/router/RouterFilter.java b/governance/src/main/java/org/apache/servicecomb/router/RouterFilter.java
index 696b859..78145bf 100644
--- a/governance/src/main/java/org/apache/servicecomb/router/RouterFilter.java
+++ b/governance/src/main/java/org/apache/servicecomb/router/RouterFilter.java
@@ -53,16 +53,12 @@
     if (StringUtils.isEmpty(targetServiceName)) {
       return list;
     }
-    /**
-     * 1.init and cache
-     */
+    // 1.init and cache
     if (!routerRuleCache.doInit(targetServiceName)) {
       LOGGER.debug("route management init failed");
       return list;
     }
-    /**
-     * 2.match rule
-     */
+    // 2.match rule
     PolicyRuleItem invokeRule = routerRuleMatcher.match(targetServiceName, headers);
 
     if (invokeRule == null) {
@@ -72,9 +68,7 @@
 
     LOGGER.debug("route management match rule success: {}", invokeRule);
 
-    /**
-     * 3.distribute select endpoint
-     */
+    // 3.distribute select endpoint
     List<T> resultList = distributer.distribute(targetServiceName, list, invokeRule);
 
     LOGGER.debug("route management distribute rule success: {}", resultList);
diff --git a/handlers/handler-loadbalance/src/main/java/org/apache/servicecomb/loadbalance/filter/PriorityInstancePropertyDiscoveryFilter.java b/handlers/handler-loadbalance/src/main/java/org/apache/servicecomb/loadbalance/filter/PriorityInstancePropertyDiscoveryFilter.java
index 8bbceef..938f1bd 100644
--- a/handlers/handler-loadbalance/src/main/java/org/apache/servicecomb/loadbalance/filter/PriorityInstancePropertyDiscoveryFilter.java
+++ b/handlers/handler-loadbalance/src/main/java/org/apache/servicecomb/loadbalance/filter/PriorityInstancePropertyDiscoveryFilter.java
@@ -116,7 +116,7 @@
     return new InstancePropertyDiscoveryFilter().getOrder() + 1;
   }
 
-  class PriorityInstanceProperty {
+  static class PriorityInstanceProperty {
     private static final int MAX_LENGTH = 10000;
 
     private static final String SEPARATOR = ".";
diff --git a/handlers/handler-loadbalance/src/test/java/org/apache/servicecomb/loadbalance/TestLoadBalanceHandler2.java b/handlers/handler-loadbalance/src/test/java/org/apache/servicecomb/loadbalance/TestLoadBalanceHandler2.java
index dc1ee62..8857a70 100644
--- a/handlers/handler-loadbalance/src/test/java/org/apache/servicecomb/loadbalance/TestLoadBalanceHandler2.java
+++ b/handlers/handler-loadbalance/src/test/java/org/apache/servicecomb/loadbalance/TestLoadBalanceHandler2.java
@@ -237,7 +237,7 @@
     Assertions.assertEquals("rest://localhost:9091", server.getEndpoint().getEndpoint());
   }
 
-  public class IsolationEndpointListener {
+  public static class IsolationEndpointListener {
     Holder<Integer> count;
 
     public IsolationEndpointListener(Holder<Integer> count) {
diff --git a/integration-tests/it-consumer/src/main/java/org/apache/servicecomb/it/testcase/TestDownloadSlowStreamEdge.java b/integration-tests/it-consumer/src/main/java/org/apache/servicecomb/it/testcase/TestDownloadSlowStreamEdge.java
index 8c9cfa5..a8f8941 100644
--- a/integration-tests/it-consumer/src/main/java/org/apache/servicecomb/it/testcase/TestDownloadSlowStreamEdge.java
+++ b/integration-tests/it-consumer/src/main/java/org/apache/servicecomb/it/testcase/TestDownloadSlowStreamEdge.java
@@ -30,11 +30,6 @@
 
   @Test
   public void clearInputStreamAfterDisconnect() throws IOException {
-//    URL url = new URL(client.getUrlPrefix() + "/slowInputStream");
-//    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
-//    conn.getInputStream().close();
-//    conn.disconnect();
-
     OkHttpClient httpClient = new OkHttpClient();
     Request request = new Request.Builder().url(client.getUrlPrefix() + "/slowInputStream")
         .build();
diff --git a/integration-tests/it-producer/src/main/java/org/apache/servicecomb/it/schema/PageSchema.java b/integration-tests/it-producer/src/main/java/org/apache/servicecomb/it/schema/PageSchema.java
deleted file mode 100644
index 344805d..0000000
--- a/integration-tests/it-producer/src/main/java/org/apache/servicecomb/it/schema/PageSchema.java
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.servicecomb.it.schema;
-
-//@RestSchema(schemaId = "page")
-//@RequestMapping(path = "/v1/page")
-public class PageSchema {
-//  @GetMapping
-//  public Page<User> page() {
-//    return null;
-//  }
-}
diff --git a/integration-tests/tracing-tests/src/test/java/org/apache/servicecomb/tests/tracing/TracedJaxrsController.java b/integration-tests/tracing-tests/src/test/java/org/apache/servicecomb/tests/tracing/TracedJaxrsController.java
index 568fd63..47503e8 100644
--- a/integration-tests/tracing-tests/src/test/java/org/apache/servicecomb/tests/tracing/TracedJaxrsController.java
+++ b/integration-tests/tracing-tests/src/test/java/org/apache/servicecomb/tests/tracing/TracedJaxrsController.java
@@ -38,9 +38,6 @@
 
   private final Random random = new Random();
 
-  //@Autowired
-  //private RestTemplate template;
-
   private TracedPojo tracedPojo;
 
   @Autowired
diff --git a/providers/provider-rest-common/src/test/java/org/apache/servicecomb/provider/rest/common/TestRestProducers.java b/providers/provider-rest-common/src/test/java/org/apache/servicecomb/provider/rest/common/TestRestProducers.java
index 1d276ea..c53b943 100644
--- a/providers/provider-rest-common/src/test/java/org/apache/servicecomb/provider/rest/common/TestRestProducers.java
+++ b/providers/provider-rest-common/src/test/java/org/apache/servicecomb/provider/rest/common/TestRestProducers.java
@@ -23,7 +23,7 @@
 
 public class TestRestProducers {
   @RestSchema(schemaId = "test")
-  public class RestSchemaForTest {
+  public static class RestSchemaForTest {
   }
 
   RestProducers producer = new RestProducers();
diff --git a/service-registry/registry-service-center/src/test/java/org/apache/servicecomb/serviceregistry/registry/TestRemoteServiceRegistry.java b/service-registry/registry-service-center/src/test/java/org/apache/servicecomb/serviceregistry/registry/TestRemoteServiceRegistry.java
index ac68a14..dc769fa 100644
--- a/service-registry/registry-service-center/src/test/java/org/apache/servicecomb/serviceregistry/registry/TestRemoteServiceRegistry.java
+++ b/service-registry/registry-service-center/src/test/java/org/apache/servicecomb/serviceregistry/registry/TestRemoteServiceRegistry.java
@@ -40,7 +40,7 @@
 import org.junit.jupiter.api.Assertions;
 
 public class TestRemoteServiceRegistry {
-  class TestingRemoteServiceRegistry extends RemoteServiceRegistry {
+  static class TestingRemoteServiceRegistry extends RemoteServiceRegistry {
     public TestingRemoteServiceRegistry(EventBus eventBus, ServiceRegistryConfig serviceRegistryConfig,
         Configuration configuration) {
       super(eventBus, serviceRegistryConfig, configuration);
diff --git a/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/ApiProcessorTest.java b/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/ApiProcessorTest.java
index 4319d5e..dea6c69 100644
--- a/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/ApiProcessorTest.java
+++ b/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/ApiProcessorTest.java
@@ -35,14 +35,14 @@
 
 public class ApiProcessorTest {
   @Api(tags = {"tag1", "tag2", "", "tag1"})
-  private class SwaggerTestTarget {
+  private static class SwaggerTestTarget {
     public void op() {
 
     }
   }
 
   @Api
-  private class SwaggerTestTargetWithNoTag {
+  private static class SwaggerTestTargetWithNoTag {
     public void op() {
 
     }
@@ -51,18 +51,18 @@
   @SwaggerDefinition(consumes = {"", " "}, produces = {"", " "})
   @Api(consumes = MediaType.TEXT_PLAIN + " , " + MediaType.APPLICATION_JSON,
       produces = MediaType.APPLICATION_XML + "," + MediaType.APPLICATION_JSON)
-  private class OverrideEmptyConsumesAndProduces {
+  private static class OverrideEmptyConsumesAndProduces {
   }
 
   @SwaggerDefinition(consumes = MediaType.MULTIPART_FORM_DATA, produces = MediaType.MULTIPART_FORM_DATA)
   @Api(consumes = MediaType.TEXT_PLAIN + " , " + MediaType.APPLICATION_JSON,
       produces = MediaType.APPLICATION_XML + "," + MediaType.APPLICATION_JSON)
-  private class OverWriteValidConsumesAndProduces {
+  private static class OverWriteValidConsumesAndProduces {
   }
 
   @Api(consumes = MediaType.TEXT_PLAIN + " , " + MediaType.APPLICATION_JSON,
       produces = MediaType.APPLICATION_XML + "," + MediaType.APPLICATION_JSON)
-  private class pureApi {
+  private static class pureApi {
   }
 
   @Test
diff --git a/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/SwaggerDefinitionProcessorTest.java b/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/SwaggerDefinitionProcessorTest.java
index ea4e29b..3cf949b 100644
--- a/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/SwaggerDefinitionProcessorTest.java
+++ b/swagger/swagger-generator/generator-core/src/test/java/org/apache/servicecomb/swagger/generator/core/processor/annotation/SwaggerDefinitionProcessorTest.java
@@ -56,16 +56,16 @@
           license = @License(name = "licenseName")),
       consumes = {MediaType.APPLICATION_JSON, MediaType.TEXT_PLAIN},
       produces = {MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
-  private class SwaggerTestTarget {
+  private static class SwaggerTestTarget {
   }
 
   @Api(consumes = MediaType.APPLICATION_XML, produces = MediaType.TEXT_PLAIN)
   @SwaggerDefinition(consumes = "", produces = "")
-  private class SwaggerTestTarget_EmptyMediaType {
+  private static class SwaggerTestTarget_EmptyMediaType {
   }
 
   @SwaggerDefinition()
-  private class EmptySwaggerDefinition {
+  private static class EmptySwaggerDefinition {
   }
 
   @SwaggerDefinition(securityDefinition = @SecurityDefinition(
@@ -84,7 +84,7 @@
               }),
       })
   )
-  private class SecurityOAuth2 {
+  private static class SecurityOAuth2 {
   }
 
   @SwaggerDefinition(securityDefinition = @SecurityDefinition(
@@ -95,7 +95,7 @@
           @ApiKeyAuthDefinition(key = "apikey-desc", description = "desc", in = ApiKeyLocation.QUERY, name = "q2")
       }
   ))
-  private class SecurityApiKey {
+  private static class SecurityApiKey {
   }
 
   @SwaggerDefinition(securityDefinition = @SecurityDefinition(
@@ -105,7 +105,7 @@
           @BasicAuthDefinition(key = "basic-desc", description = "desc")
       }
   ))
-  private class SecurityBasic {
+  private static class SecurityBasic {
   }
 
   @Test
diff --git a/swagger/swagger-invocation/invocation-core/src/test/java/org/apache/servicecomb/swagger/invocation/response/TestResponsesMeta.java b/swagger/swagger-invocation/invocation-core/src/test/java/org/apache/servicecomb/swagger/invocation/response/TestResponsesMeta.java
index c73d308..4f07085 100644
--- a/swagger/swagger-invocation/invocation-core/src/test/java/org/apache/servicecomb/swagger/invocation/response/TestResponsesMeta.java
+++ b/swagger/swagger-invocation/invocation-core/src/test/java/org/apache/servicecomb/swagger/invocation/response/TestResponsesMeta.java
@@ -29,7 +29,7 @@
 import org.junit.jupiter.api.Assertions;
 
 public class TestResponsesMeta {
-  class ResponseMetaImpl {
+  static class ResponseMetaImpl {
     @ApiResponses({@ApiResponse(code = 400, response = String.class, message = ""),
         @ApiResponse(
             code = 401,
diff --git a/swagger/swagger-invocation/invocation-springmvc/src/test/java/org/apache/servicecomb/swagger/invocation/converter/TestPartToMultipartFile.java b/swagger/swagger-invocation/invocation-springmvc/src/test/java/org/apache/servicecomb/swagger/invocation/converter/TestPartToMultipartFile.java
index 114e0fb..e0e3cf4 100644
--- a/swagger/swagger-invocation/invocation-springmvc/src/test/java/org/apache/servicecomb/swagger/invocation/converter/TestPartToMultipartFile.java
+++ b/swagger/swagger-invocation/invocation-springmvc/src/test/java/org/apache/servicecomb/swagger/invocation/converter/TestPartToMultipartFile.java
@@ -120,7 +120,7 @@
     Assertions.assertEquals(size, multipartFile.getSize());
   }
 
-  class ByteArrayInputStreamForTest extends ByteArrayInputStream {
+  static class ByteArrayInputStreamForTest extends ByteArrayInputStream {
     boolean closed;
 
     public ByteArrayInputStreamForTest(byte[] buf) {
diff --git a/transports/transport-rest/transport-rest-vertx/src/test/java/org/apache/servicecomb/transport/rest/vertx/TestAbstractVertxHttpDispatcher.java b/transports/transport-rest/transport-rest-vertx/src/test/java/org/apache/servicecomb/transport/rest/vertx/TestAbstractVertxHttpDispatcher.java
index 6fefb81..2b1e157 100644
--- a/transports/transport-rest/transport-rest-vertx/src/test/java/org/apache/servicecomb/transport/rest/vertx/TestAbstractVertxHttpDispatcher.java
+++ b/transports/transport-rest/transport-rest-vertx/src/test/java/org/apache/servicecomb/transport/rest/vertx/TestAbstractVertxHttpDispatcher.java
@@ -41,7 +41,7 @@
 
 @FixMethodOrder(MethodSorters.NAME_ASCENDING)
 public class TestAbstractVertxHttpDispatcher {
-  class AbstractVertxHttpDispatcherForTest extends AbstractVertxHttpDispatcher {
+  static class AbstractVertxHttpDispatcherForTest extends AbstractVertxHttpDispatcher {
     @Override
     public int getOrder() {
       return 0;