gradeChangeType property
The type of grade change at this time in the submission grade history. Possible string values are:
- "UNKNOWN_GRADE_CHANGE_TYPE" : No grade change type specified. This should never be returned.
 - "DRAFT_GRADE_POINTS_EARNED_CHANGE" : A change in the numerator of the draft grade.
 - "ASSIGNED_GRADE_POINTS_EARNED_CHANGE" : A change in the numerator of the assigned grade.
 - "MAX_POINTS_CHANGE" : A change in the denominator of the grade.
 
Implementation
core.String? gradeChangeType;