Multi Instance support not valid

Multi Instance support can be easily broken by different dataInputAssociation order, since collection expression is taken from dataInputAssociations without verifying the values given in loopDataInputRef, github reference: https://github.com/droolsjbpm/jbpm/blob/master/jbpm-bpmn2/src/main/java/org/jbpm/bpmn2/xml/TaskHandler.java#L195

Moreover since jBPM is now more strict about variable types multi instance needs to deal with data types as well to avoid problems with recognizing right data type.