Spell and code style optimization. (#10634)

diff --git a/dubbo-common/src/main/java/org/apache/dubbo/common/compiler/support/JdkCompiler.java b/dubbo-common/src/main/java/org/apache/dubbo/common/compiler/support/JdkCompiler.java
index 443690b..cebeaf7 100644
--- a/dubbo-common/src/main/java/org/apache/dubbo/common/compiler/support/JdkCompiler.java
+++ b/dubbo-common/src/main/java/org/apache/dubbo/common/compiler/support/JdkCompiler.java
@@ -55,7 +55,7 @@
 
     private final JavaCompiler compiler = ToolProvider.getSystemJavaCompiler();
 
-    private final DiagnosticCollector<JavaFileObject> diagnosticCollector = new DiagnosticCollector<JavaFileObject>();
+    private final DiagnosticCollector<JavaFileObject> diagnosticCollector = new DiagnosticCollector<>();
 
     private final ClassLoaderImpl classLoader;
 
@@ -83,7 +83,7 @@
                 && (!"sun.misc.Launcher$AppClassLoader".equals(loader.getClass().getName()))) {
             try {
                 URLClassLoader urlClassLoader = (URLClassLoader) loader;
-                List<File> files = new ArrayList<File>();
+                List<File> files = new ArrayList<>();
                 for (URL url : urlClassLoader.getURLs()) {
                     files.add(new File(url.getFile()));
                 }
@@ -172,7 +172,7 @@
 
         private final ClassLoaderImpl classLoader;
 
-        private final Map<URI, JavaFileObject> fileObjects = new HashMap<URI, JavaFileObject>();
+        private final Map<URI, JavaFileObject> fileObjects = new HashMap<>();
 
         public JavaFileManagerImpl(JavaFileManager fileManager, ClassLoaderImpl classLoader) {
             super(fileManager);
@@ -224,7 +224,7 @@
 
             ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
 
-            ArrayList<JavaFileObject> files = new ArrayList<JavaFileObject>();
+            ArrayList<JavaFileObject> files = new ArrayList<>();
 
             if (location == StandardLocation.CLASS_PATH && kinds.contains(JavaFileObject.Kind.CLASS)) {
                 for (JavaFileObject file : fileObjects.values()) {
@@ -252,7 +252,7 @@
 
     private static final class ClassLoaderImpl extends ClassLoader {
 
-        private final Map<String, JavaFileObject> classes = new HashMap<String, JavaFileObject>();
+        private final Map<String, JavaFileObject> classes = new HashMap<>();
 
         ClassLoaderImpl(final ClassLoader parentClassLoader) {
             super(parentClassLoader);
diff --git a/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/AbstractDynamicConfiguration.java b/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/AbstractDynamicConfiguration.java
index b5feab0..164372d 100644
--- a/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/AbstractDynamicConfiguration.java
+++ b/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/AbstractDynamicConfiguration.java
@@ -78,7 +78,7 @@
     protected final ErrorTypeAwareLogger logger = LoggerFactory.getErrorTypeAwareLogger(getClass());
 
     /**
-     * The thread pool for workers who executes the tasks
+     * The thread pool for workers who execute the tasks
      */
     private final ThreadPoolExecutor workersThreadPool;
 
@@ -86,12 +86,12 @@
 
     private final long timeout;
 
-    public AbstractDynamicConfiguration(URL url) {
+    protected AbstractDynamicConfiguration(URL url) {
         this(getThreadPoolPrefixName(url), getThreadPoolSize(url), getThreadPoolKeepAliveTime(url), getGroup(url),
                 getTimeout(url));
     }
 
-    public AbstractDynamicConfiguration(String threadPoolPrefixName,
+    protected AbstractDynamicConfiguration(String threadPoolPrefixName,
                                         int threadPoolSize,
                                         long keepAliveTime,
                                         String group,
diff --git a/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/DynamicConfiguration.java b/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/DynamicConfiguration.java
index fcd08eb..fc505d5 100644
--- a/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/DynamicConfiguration.java
+++ b/dubbo-common/src/main/java/org/apache/dubbo/common/config/configcenter/DynamicConfiguration.java
@@ -23,7 +23,7 @@
 /**
  * Dynamic Configuration
  * <br/>
- * From the use scenario internally inside framework, there're mainly three kinds of methods:
+ * From the use scenario internally inside framework, there are mainly three kinds of methods:
  * <ol>
  * <li>{@link #getProperties(String, String, long)}, get configuration file from Config Center at start up.</li>
  * <li>{@link #addListener(String, String, ConfigurationListener)}/ {@link #removeListener(String, String, ConfigurationListener)}