private void initColumnListAndAddCol(String colName) {
        if (this.columnList == null) {
            this.columnList = new ArrayList<String>();
        }
        this.columnList.add(colName);
    }
Builder for the GetProjectionsSpec. This is a projection specification for tables returned from the HMS.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/client/builder/GetTableProjectionsSpecBuilder.java