question: public static StringBuilder makeWhereStringFromFields ( StringBuilder sb , List < ModelField > modelFields , Map < String , Object > fields , String operator , List < EntityConditionParam > entityConditionParams ) { if ( modelFields . size ( ) < 1 ) { return sb ; } Iterator < ModelField > iter = modelFields . iterator ( ) ; while ( iter . hasNext ( ) ) { Object item = iter . next ( ) ; Object name = null ; ModelField modelField = null ; if ( item instanceof ModelField ) { modelField = ( ModelField ) item ; sb . append ( modelField . getColValue ( ) ) ; name = modelField . getName ( ) ; } else { sb . append ( item ) ; name = item ; } Object fieldValue = fields . get ( name ) ; if ( fieldValue != null && fieldValue != GenericEntity . NULL_FIELD ) { sb . append ( '=' ) ; addValue ( sb , modelField , fieldValue , entityConditionParams ) ; } else { sb . append ( " IS NULL" ) ; } if ( iter . hasNext ( ) ) { sb . append ( ' ' ) ; sb . append ( operator ) ; sb . append ( ' ' ) ; } } return sb ; }
target:  Makes a WHERE clause String with "<col name>=?" if not null or "<col name> IS null" if null, all AND separated 