src/main/java/com/authlete/jaxrs/util/JaxRsUtils.java
public static <TKey, TValue> MultivaluedMap<TKey, TValue>
            createMultivaluedMap(Map<TKey, TValue[]> data)
    {
        MultivaluedMap<TKey, TValue> target
            = new MultivaluedHashMap<TKey, TValue>();

        return putAll(target, data);
    }
public static <TKey, TValue> MultivaluedMap<TKey, TValue>
            createMultivaluedMap(Map<TKey, TValue[]> data)
    {
        MultivaluedMap<TKey, TValue> target
            = new MultivaluedHashMap<TKey, TValue>();

        return putAll(target, data);
    }
Create a {@code Map<TKey, TValue>} instance from a
{@code Map<TKey, TValue[]} instance.

@param data
Input data.

@return
A new instance which contains all the entries
in the input data. If the input data is {@code null}
or empty, an empty {@code MultivaluedMap} instance
is returned.