question: private void validateCloumns ( Map < String , Object > columnNameToTypeMap ) { if ( columnNameToTypeMap == null ) { throw new IllegalArgumentException ( "columnNameToTypeMap should not be null" ) ; } for ( Map . Entry < String , Object > entry : columnNameToTypeMap . entrySet ( ) ) { Object objValue = entry . getValue ( ) ; if ( objValue == null ) { throw new IllegalArgumentException ( "columnName=" + entry . getKey ( ) + " has null type" ) ; } if ( objValue instanceof Class < ? > ) { continue ; } if ( objValue instanceof String ) { try { entry . setValue ( Class . forName ( ( String ) objValue ) ) ; } catch ( ClassNotFoundException e ) { throw new IllegalArgumentException ( "type field validation failed. e=" , e ) ; } } } }
target:  make sure the type is valid type and restore the value back with Class objects