TBD-3909 fix: Impala principal is not contained in the exported context

and Impala principal text box can not be edited after exported context.
when we click revert button,Impala principal text box should return
original value.
https://jira.talendforge.org/browse/TBD-3909

main/plugins/org.talend.metadata.managment.ui/src/main/java/org/talend/metadata/managment/ui/utils/DBConnectionContextUtils.java

@@ -1273,6 +1273,12 @@ public final class DBConnectionContextUtils {
                     ContextParameterUtils.getOriginalValue(contextType, maprticket_Duration));
 
         }
+        // for Impala
+        if (EDatabaseTypeName.IMPALA.equals(EDatabaseTypeName.getTypeFromDbType(conn.getDatabaseType()))) {
+            String impalaPrin = conn.getParameters().get(ConnParameterKeys.IMPALA_AUTHENTICATION_PRINCIPLA);
+            conn.getParameters().put(ConnParameterKeys.IMPALA_AUTHENTICATION_PRINCIPLA,
+                    ContextParameterUtils.getOriginalValue(contextType, impalaPrin));
+        }
         // revert the context value in the hadoop properties dialog if it is hive or hbase
         String hadoopPropertiesJson = transformContextModeToOriginal(getHiveOrHbaseHadoopProperties(conn), contextType);
         setAdditionalHadoopProperties(conn, hadoopPropertiesJson);

main/plugins/org.talend.repository.metadata/src/main/java/org/talend/repository/ui/wizards/metadata/connection/database/DatabaseForm.java

@@ -2376,6 +2376,11 @@ public class DatabaseForm extends AbstractForm {
         }
     }
 
+    private void adaptImpalaHadoopPartEditable() {
+        useKerberosForImpala.setEnabled(!isContextMode());
+        impalaPrincipalTxt.setEditable(!isContextMode());
+    }
+
     private void updateHadoopProperties(boolean isEditable) {
         refreshHadoopProperties();
         refreshHiveJdbcProperties();
@@ -5795,6 +5800,10 @@ public class DatabaseForm extends AbstractForm {
             adaptHbaseHadoopPartEditable();
             updateHadoopProperties(!isContextMode());
         }
+        if (isImpalaDBConnSelected()) {
+            adaptImpalaHadoopPartEditable();
+            updateHadoopProperties(!isContextMode());
+        }
     }
 
     public boolean isDbTypenull() {