jrapidoc-rest-plugin/src/main/java/org/jboss/resteasy/util/Types.java
public static Class<?> getTypeArgument(Type genericType) {
        if (!(genericType instanceof ParameterizedType))
            return null;
        ParameterizedType parameterizedType = (ParameterizedType) genericType;
        Class<?> typeArg = (Class<?>) parameterizedType.getActualTypeArguments()[0];
        return typeArg;
    }
public static Class<?> getTypeArgument(Type genericType) {
        if (!(genericType instanceof ParameterizedType))
            return null;
        ParameterizedType parameterizedType = (ParameterizedType) genericType;
        Class<?> typeArg = (Class<?>) parameterizedType.getActualTypeArguments()[0];
        return typeArg;
    }
Returns the type argument from a parameterized type

@param genericType
@return null if there is no type parameter