Merge branch 'labkit-spec/update-fields' into 'master'

    # email reply.

    GL_SENT_NOTIFICATION_ID = "gl_sent_notification_id"

    # Free-form supplementary details about a log event that do not have a

    # dedicated field. Use sparingly for human-readable context. Avoid logging

    # secrets or PII, and sanitize values that may contain control characters

    # (e.g. newlines) to prevent log injection.

    ADDITIONAL_DETAILS = "additional_details"

    # Maps each field constant to its logging field variant version.

    # A version of 0 means the field is not yet assigned to any variant.

    VARIANT_VERSION = {

      CALLER_ID => 1,

      ROOT_CALLER_ID => 0,

      GL_SENT_NOTIFICATION_ID => 0,

      ADDITIONAL_DETAILS => 0,

    }.freeze

    # Get the constant name for a field value