1. A method comprising: obtaining an indication of a model element of a first model element type which is to be migrated to a model element of a second model element type, wherein a diagrammatic representation of the model element of the first model element type is present in a diagram of a modeling environment, and wherein the diagrammatic representation of the model element of the first model element type comprises one or more properties; and automatically migrating, by a processor, the model element of the first model element type to the model element of the second model element type, wherein the automatically migrating migrates a relationship between the model element of the first model element type and a related model element to a relationship between the model element of the second model element type and the related model element, in which a replacement relationship type is applied to the relationship between the model element of the second model element type and the related model element, and wherein the automatically migrating comprises: identifying a relationship type of the relationship between the model element of the first model element type and the related model element; determining whether the identified relationship type between the model element of the first model element type and the related model element is a valid type of relationship that may exist as between the second model element type and a model element type of the related model element, wherein the determining comprises checking a model element type relationship table indicating valid relationship types that may exist as between model element types, wherein the identified relationship type is determined to be invalid as between the second model element type and the model element type of the related model element based on the model element type relationship table lacking a valid relationship type as between the second model element type and the model element type of the related model element; based on determining that the identified relationship type is invalid as between the second model element type and the model element type of the related model element, identifying the replacement relationship type which is a valid type of relationship that may exist as between the second model element type and the model element type of the related model element; obtaining the identified replacement relationship type; instantiating a new model element with the second model element type and creating a relationship between the new model element and the related model element, wherein the new model element is the model element of the second model element type, and the creating the relationship between the new model element and the related model element uses the identified replacement relationship type to automatically create, with the identified replacement relationship type, the relationship between the new model element and the related model element; and preserving the one or more properties of the diagrammatic representation of the model element of the first model element type in a diagrammatic representation of the new model element, the preserving the one or more properties of the diagrammatic representation of the model element of the first model element type comprising: obtaining the one or more properties; applying the obtained one or more properties to the diagrammatic representation of the new model element; and replacing the diagrammatic representation of the model element of the first model element type with the diagrammatic representation of the new model element in the diagram.