public List<Token> getMessage(final long messageId)
    {
        return messagesByIdMap.get(messageId);
    }
Get the getMessage for a given identifier.

@param messageId to get.
@return the List of {@link Token}s representing the message or null if the id is not found.
sbe-tool/src/main/java/uk/co/real_logic/sbe/ir/Ir.java