code: protected JvmTypeParameter findMappedParameter(JvmTypeParameter parameter,
  			Map<JvmTypeParameter, LightweightMergedBoundTypeArgument> mapping, Collection<JvmTypeParameter> visited) {
  		for(Map.Entry<JvmTypeParameter, LightweightMergedBoundTypeArgument> entry: mapping.entrySet()) {
  			LightweightMergedBoundTypeArgument reference = entry.getValue();
  			JvmType type = reference.getTypeReference().getType();
  			if (parameter == type) {
  				if (visited.add(entry.getKey()))
  					return entry.getKey();
  				return null;
  			}
  		}
  		return null;
  	}
docs: /* @Nullable