question: public void addField ( String name , String value ) throws IOException { if ( name == null ) { throw new IllegalArgumentException ( "Name cannot be null or empty." ) ; } if ( formData . length ( ) > 0 ) { formData . append ( "&" ) ; } formData . append ( name + "=" ) ; if ( value != null ) { formData . append ( URLEncoder . encode ( value , charset ) ) ; } }
target:  Writes a string field value.