A SysML Diagram is a specialization of a UML Diagram
String type = myDiagram.getProperty(SysMLDiagramKind.SYSML_PROPERTY_KEY);
Diagram umlDiagram = model.create(UMLPackage.Literals.DIAGRAM); umlDiagram.setSemanticTypeInfo(UMLDiagramKind.CLASS_DIAGRAM.getLiteral()); umlDiagram.setProperty(SysMLDiagramKind.SYSML_PROPERTY_KEY, SysMLDiagramKind.SYSML_BLOCK_DEFINITION_DIAGRAM.getLiteral());All SysML Diagram kinds are available in the Class
com.sodius.mdw.metamodel.uml21.xmi.di.SysMLDiagramKind
.