code: private static boolean mappingCompatible(EntitySchema oldSchema,
        EntitySchema newSchema) {
      for (FieldMapping oldFieldMapping : oldSchema.getColumnMappingDescriptor()
          .getFieldMappings()) {
        FieldMapping newFieldMapping = newSchema.getColumnMappingDescriptor()
            .getFieldMapping(oldFieldMapping.getFieldName());
        if (newFieldMapping != null) {
          if (!oldFieldMapping.equals(newFieldMapping)) {
            return false;
          }
        }
      }
      return true;
    }
docs: Ensure that the column mappings for the shared fields between the old and
  new schema haven't changed.
  
  @param oldSchema
  @param newSchema
  @return true if the mappings are compatible, false if not.