Interface MessageMetadata

public sealed interface MessageMetadata
Immutable exact-name, single-valued metadata local to a message envelope.

Local metadata follows the same message envelope while it is used in-process. A newly created message starts with empty local metadata unless its builder or implementation explicitly supplies a snapshot. Local metadata is separate from portable headers; connectors and generic message mappers must never serialize it or map it to a transport. Publishing a local value requires an explicit, application-controlled promotion to a portable header, including any necessary redaction and size limit.

This interface is sealed because its single abstract accessor would otherwise make it a lambda target. Lambdas cannot implement the value-based Object.equals(Object) and Object.hashCode() required by this type. Keeping implementations under Helidon control also guarantees value-independent Object.toString() output and a stable, immutable, non-null value map containing no null names or values.

  • Method Details

    • empty

      static MessageMetadata empty()
      Empty local metadata.
      Returns:
      empty metadata

    • builder

      static MessageMetadata.Builder builder()
      Create a mutable builder which produces immutable snapshots.
      Returns:
      builder

    • builder

      static MessageMetadata.Builder builder(MessageMetadata metadata)
      Create a mutable builder from existing metadata.
      Parameters:
      metadata - existing metadata
      Returns:
      builder
      Throws:
      NullPointerException - if metadata is null

    • values

      Map<String, MessageHeaderValue> values()
      Immutable exact-name values.
      Returns:
      stable, immutable, non-null metadata values

    • size

      default int size()
      Number of metadata values.
      Returns:
      value count

    • isEmpty

      default boolean isEmpty()
      Whether there are no metadata values.
      Returns:
      whether empty

    • contains

      default boolean contains(String name)
      Whether an exact metadata name is present.
      Parameters:
      name - exact metadata name
      Returns:
      whether present

    • value

      default Optional<MessageHeaderValue> value(String name)
      Value with an exact metadata name.
      Parameters:
      name - exact metadata name
      Returns:
      metadata value, or empty when absent

    • text

      default Optional<String> text(String name)
      Text value with an exact metadata name.

      This method throws when the value exists but is not a MessageHeaderValue.TextValue; it never stringifies typed values.

      Parameters:
      name - exact metadata name
      Returns:
      text value, or empty only when absent
      Throws:
      IllegalStateException - if the value is present but is not text