code: function getKeyPropertyNames(context) {
    const keyPropertyNames = context.streamProcessing.keyPropertyNames;
    return Array.isArray(keyPropertyNames) ? keyPropertyNames :
      typeof keyPropertyNames === 'string' ? toPropertyNamesArray(keyPropertyNames) : [];
  }
docs: Returns the names of all of the message key properties configured on the given context, which are used to extract a
  message's key(s), which uniquely identify the entity or subject of a message.
  @param {StreamProcessing} context - the context from which to fetch the message key property names
  @returns {string[]} the message key property names if any; otherwise an empty array