assertThat(desc.getRawClass(), is(sameClass(Map.class)));

        final ParameterizedClassDesc[] args = desc.getArguments();
        assertThat(args.length, is(2));

        final ParameterizedClassDesc arg1 = args[0];
        assertThat(arg1.getRawClass(), is(sameClass(String.class)));
        assertThat(arg1.getArguments(), is(nullValue()));

        final ParameterizedClassDesc arg2 = args[1];

        if (!Collection.class.isAssignableFrom(fieldType) || !isParameterized()) {
            return null;
        }
        final ParameterizedClassDesc pcd = parameterizedClassDesc.getArguments()[0];
        if (pcd == null) {
            return null;
        }
        return pcd.getRawClass();
    }

    @Override
    public Class<?> getKeyClassOfMap() {

        if (!Collection.class.isAssignableFrom(parameterTypes[index]) || !isParameterized(index)) {
            return null;
        }
        final ParameterizedClassDesc pcd = parameterizedClassDescs[index].getArguments()[0];
        if (pcd == null) {
            return null;
        }
        return pcd.getRawClass();
    }

    @Override
    public Class<?> getKeyClassOfMap(final int index) {

    }

    @Override
    public ParameterizedClassDesc[] getArguments() {
        return arguments;
    }

    /**
     * Sets an array of {@link ParameterizedClassDesc} representing type arguments.
     *
     * @param arguments
     *            An array of {@link ParameterizedClassDesc} representing type arguments
     */
    public void setArguments(final ParameterizedClassDesc[] arguments) {

     * </p>
     *
     * @return an array of {@link ParameterizedClassDesc} representing the type arguments
     * @see ParameterizedType#getActualTypeArguments()
     */
    ParameterizedClassDesc[] getArguments();