code: private void confirmMatchForDsTypeModel(ValidationResult result,
                                              DsTypeModel typeModel,
                                              String contentModelPid,
                                              ObjectInfo object) {
          String id = typeModel.getId();
          DatastreamInfo dsInfo = object.getDatastreamInfo(id);
          if (dsInfo == null) {
              // If there is no datastream by that name, nothing to check.
              result.addNote(ValidationResultNotation
                      .noMatchingDatastreamId(contentModelPid, id));
              return;
          }
  
          Collection<Form> forms = typeModel.getForms();
          if (forms.isEmpty()) {
              // If the type model has no forms, it's an automatic match.
              return;
          }
  
          // Otherwise, the datastream must meet the constraints of at least one form.
          for (Form form : forms) {
              if (meetsConstraint(dsInfo.getMimeType(), form.getMimeType())
                      && meetsConstraint(dsInfo.getFormatUri(), form
                              .getFormatUri())) {
                  return;
              }
          }
          result.addNote(ValidationResultNotation
                  .datastreamDoesNotMatchForms(contentModelPid, id));
      }
docs: The object must have a datastream to match each dsTypeModel in the
  content model. Matching a dsTypeModel means equal IDs and an acceptable
  form.