code: def _get_imports_h(self, data_types):
          
          if not isinstance(data_types, list):
              data_types = [data_types]
  
          import_classes = []
  
          for data_type in data_types:
  
              if is_user_defined_type(data_type):
                  import_classes.append(fmt_class_prefix(data_type))
  
              for field in data_type.all_fields:
                  data_type, _ = unwrap_nullable(field.data_type)
  
                  # unpack list or map
                  while is_list_type(data_type) or is_map_type(data_type):
                      data_type = (data_type.value_data_type if
                          is_map_type(data_type) else data_type.data_type)
  
                  if is_user_defined_type(data_type):
                      import_classes.append(fmt_class_prefix(data_type))
  
          import_classes = list(set(import_classes))
          import_classes.sort()
  
          return import_classes
docs: Emits all necessary header file imports for the given Stone data type.