The behavior of the @RestHeader annotation is different from the @HeaderParam annotation when the parameter is of type List #31866
Description
The @RestHeader javadoc says :
/*
* Equivalent of HeaderParam but with optional name.
*/
And the javadoc of HeaderParam say that :
/**
* Binds the value(s) of a HTTP header to a resource method parameter,
* resource class field, or resource class bean property. A default value
* can be specified using the {@link DefaultValue} annotation.
*
* The type {@code T} of the annotated parameter, field or property
* must either:
* <ol>
* <li>Be a primitive type</li>
* <li>Have a constructor that accepts a single {@code String} argument</li>
* <li>Have a static method named {@code valueOf} or {@code fromString}
* that accepts a single
* {@code String} argument (see, for example, {@link Integer#valueOf(String)})</li>
* <li>Have a registered implementation of {@link javax.ws.rs.ext.ParamConverterProvider}
* JAX-RS extension SPI that returns a {@link javax.ws.rs.ext.ParamConverter}
* instance capable of a "from string" conversion for the type.</li>
* <li>Be {@code List<T>}, {@code Set<T>} or
* {@code SortedSet<T>}, where {@code T} satisfies 2, 3 or 4 above.
* The resulting collection is read-only.</li>
* </ol>
*
* /
But the behavior of @RestHeader is different when the parameter is a List :
by example a method like that :
Response getSomething(@RestHeader("Prefer") List prefers);
Throw this kind of exception :
ClassCast class java.util.ImmutableCollections$List12 cannot be cast to class java.lang.String (java.util.ImmutableCollections$List12 and java.lang.String are in module java.base of loader 'bootstrap')
since 2.8 and it can be reproduced in 3.0.0.Alpha5