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Status

Current state: Under Discussion

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Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

Headers is a part of public APIs but the usage of Headers is a bit chaos to users.

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We can't improve Headers right now by reason of deprecation cycles. This KIP plans to deprecate and offer default implementation (java.lang.UnsupportedOperationException) to all setters of Headers so we can cleanup all setters to make it be readonly in next major and users are able to remove all useless implementation from their Headers in this patch.

Public Interfaces

The following methods of Headers are deprecated.

    @Deprecated
    default Headers add(Header header) throws IllegalStateException {
        throw new UnsupportedOperationException("this method is deprecated");
    }

    @Deprecated
    default Headers add(String key, byte[] value) throws IllegalStateException {
        throw new UnsupportedOperationException("this method is deprecated");
    }

    @Deprecated
    default Headers remove(String key) throws IllegalStateException {
        throw new UnsupportedOperationException("this method is deprecated");
    }

Proposed Changes

The following changes are added to Headers

1. deprecated Headers#add(Header)
2. add default implementation to Headers#add(Header)
3. deprecated Headers#add(String, byte[])
4. add default implementation to Headers#add(String, byte[])
5. deprecated Headers#add(String)
6. add default implementation to Headers#add(String)

Compatibility, Deprecation, and Migration Plan

C: No methods are removed so compatibility issue does not exist

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MP: User-implemented Headers can remove the deprecated methods

Rejected Alternatives

n/a