[bugfix][plugin][hdfswriter] Fix NullPointerException when writing Pa…

…rquet file with null string field value

Add missing 'continue' statement to handle null string field values and prevent NullPointerException during Parquet file writing, fix #1104

plugin/writer/hdfswriter/src/main/java/com/wgzhao/addax/plugin/writer/hdfswriter/HdfsHelper.java

@@ -246,9 +246,9 @@ public static Group transportParRecord(
             String typename = columns.get(i).getString(Key.TYPE).toUpperCase();
             if (null == column || column.getRawData() == null) {
                 group.append(colName, "");
+                continue;
             }
             SupportHiveDataType columnType = SupportHiveDataType.valueOf(typename);
-            assert column != null;
             switch (columnType) {
                 case INT:
                 case INTEGER: