withHeader

Adds a key-value pair to the message header and returns the message for method chaining.

This provides a fluent API for setting header metadata. If the message is read-only, this operation may throw an exception or be ignored.

This message instance (cast to SOURCE type) to support method chaining

key

The header key to set (must not be null)

value

The header value to associate with the key (must not be null)

if the message is read-only and header modifications are not allowed

open fun withHeader(additionalSource: Map<String, String>): SOURCE

Adds all key-value pairs from the provided map to the message header and returns the message for method chaining.

This provides a fluent API for bulk setting header metadata. If the message is read-only, this operation may throw an exception or be ignored.

This message instance (cast to SOURCE type) to support method chaining

additionalSource

A map containing key-value pairs to add to the header (must not be null)

if the message is read-only and header modifications are not allowed