Specifies endpoints and which streams (audio and/or video) they receive. Supports the following keys:
- remoteParticipantId as the key containing one or more endpoint IDs.
- The keyword all for all the endpoints in a conference. You can additionally specify the new key for all the newly connected endpoints. IMPORTANT: all excludes all other keys except for new. If all and remoteParticipantId are both specified, the latter is ignored.