code: @Override
      public Multimap<URI, URI> listTypedInputs(URI operationUri) {
          if (operationUri == null) {
              return ImmutableMultimap.of();
          }
  
          ImmutableMultimap.Builder<URI, URI> result = ImmutableMultimap.builder();
          for (URI input : this.opInputMap.get(operationUri)) {
              result.putAll(input, this.modelReferencesMap.get(input));
          }
  
          return result.build();
      }
docs: Given an operation, this method obtains the list of input URIs mapped to their annotated types (i.e., modelReferences).
  Note that the same input may have several annotations indicating the type.
  
  @param operationUri the URI for which we want to obtain the inputs and their annotated types
  @return a Multimap with the inputs and their corresponding types.