[ONOS-3880, 3881] Change to static import for lesser indentation.

Change-Id: I93a39f9b0ccd019ace5900bf8ba68f7d60f228a0
diff --git a/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java b/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java
index 3f6fc40..42c753c 100644
--- a/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java
+++ b/src/main/java/org/onosproject/yangutils/parser/impl/listeners/SubModuleListener.java
@@ -17,14 +17,17 @@
 package org.onosproject.yangutils.parser.impl.listeners;
 
 import org.onosproject.yangutils.datamodel.YangSubModule;
-import org.onosproject.yangutils.parser.ParsableDataType;
 import org.onosproject.yangutils.parser.antlrgencode.GeneratedYangParser;
 import org.onosproject.yangutils.parser.exceptions.ParserException;
 import org.onosproject.yangutils.parser.impl.TreeWalkListener;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType;
-import org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation;
+
+import static org.onosproject.yangutils.parser.ParsableDataType.SUB_MODULE_DATA;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.ENTRY;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorLocation.EXIT;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorMessageConstruction.constructListenerErrorMessage;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerErrorType.*;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsEmpty;
+import static org.onosproject.yangutils.parser.impl.parserutils.ListenerValidation.checkStackIsNotEmpty;
 
 /*
  * Reference: RFC6020 and YANG ANTLR Grammar
@@ -58,9 +61,8 @@
     }
 
     /**
-     * It is called when parser receives an input matching the grammar
-     * rule (sub module), perform validations and update the data model
-     * tree.
+     * It is called when parser receives an input matching the grammar rule (sub
+     * module), perform validations and update the data model tree.
      *
      * @param listener Listener's object.
      * @param ctx context object of the grammar rule.
@@ -69,9 +71,8 @@
                                              GeneratedYangParser.SubModuleStatementContext ctx) {
 
         // Check if stack is empty.
-        ListenerValidation
-                .checkStackIsEmpty(listener, ListenerErrorType.INVALID_HOLDER, ParsableDataType.SUB_MODULE_DATA,
-                                   String.valueOf(ctx.IDENTIFIER().getText()), ListenerErrorLocation.ENTRY);
+        checkStackIsEmpty(listener, INVALID_HOLDER, SUB_MODULE_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
+                          ENTRY);
 
         YangSubModule yangSubModule = new YangSubModule();
         yangSubModule.setName(ctx.IDENTIFIER().getText());
@@ -90,19 +91,12 @@
                                             GeneratedYangParser.SubModuleStatementContext ctx) {
 
         // Check for stack to be non empty.
-        ListenerValidation.checkStackIsNotEmpty(listener, ListenerErrorType.MISSING_HOLDER,
-                                                ParsableDataType.SUB_MODULE_DATA,
-                                                String.valueOf(ctx.IDENTIFIER().getText()),
-                                                ListenerErrorLocation.EXIT);
+        checkStackIsNotEmpty(listener, MISSING_HOLDER, SUB_MODULE_DATA, String.valueOf(ctx.IDENTIFIER().getText()),
+                             EXIT);
 
         if (!(listener.getParsedDataStack().peek() instanceof YangSubModule)) {
-            throw new ParserException(
-                                      ListenerErrorMessageConstruction
-                                              .constructListenerErrorMessage(ListenerErrorType.MISSING_CURRENT_HOLDER,
-                                                                             ParsableDataType.SUB_MODULE_DATA,
-                                                                             String.valueOf(ctx.IDENTIFIER()
-                                                                                     .getText()),
-                                                                             ListenerErrorLocation.EXIT));
+            throw new ParserException(constructListenerErrorMessage(MISSING_CURRENT_HOLDER, SUB_MODULE_DATA,
+                                                                    String.valueOf(ctx.IDENTIFIER().getText()), EXIT));
         }
     }
-}
\ No newline at end of file
+}