code: public RuntimeResourceDefinition getBaseDefinition() {
  		validateSealed();
  		if (myBaseDefinition == null) {
  			myBaseDefinition = myContext.getResourceDefinition(myBaseType);
  		}
  		return myBaseDefinition;
  	}
docs: If this definition refers to a class which extends another resource definition type, this
  method will return the definition of the topmost resource. For example, if this definition
  refers to MyPatient2, which extends MyPatient, which in turn extends Patient, this method
  will return the resource definition for Patient.
  <p>
  If the definition has no parent, returns <code>this</code>
  </p>