1. A computer-implemented method for morphing entities in metamodel-based business process model and notation (BPMN) tools, the method being performed by execution of computer readable program code by at least one processor of at least one computer system, the method comprising: receiving, by a client having one or more processors, a command for an entity to be morphed from a first non-abstract entity type to a second non-abstract entity type; returning, by the client and from a modeling infrastructure (MOIN), one or more applicable non-abstract sub-types of the first non-abstract entity type or siblings of the entity based on an inheritance hierarchy in a metamodel associated with the entity, the metamodel including classes that characterize domain entities and relationships between the domain entities, the domain entities including the entity being morphed; determining, by a morphing engine being executed by the one or more processors remote from the client, the second non-abstract entity type from the one or more applicable non-abstract sub-types or siblings of the entity, the determining including calling a morphing code in a process composer plug-in being executed at the client, the morphing code creating a morphing command object via a constructor that gets, from the MOIN, a connection to the MOIN, a human readable description of the morphing command, the element to be migrated, and the class descriptor of the sub-type to which the element is to be morphed; and morphing, by the morphing engine being executed on the one or more processors, the entity from the first non-abstract entity type to the second non-abstract entity type.