Merge "Update docs for getGenericConferenceActiveChildCall"

    /**

     * Returns the child {@link Call} in a generic conference that is currently active.

     *

     * A "generic conference" is the mechanism used to support two simultaneous calls on a device

     * in CDMA networks. It is effectively equivalent to having one call active and one call on hold

     * in GSM or IMS calls. This method returns the currently active call.

     *

     * In a generic conference, the network exposes the conference to us as a single call, and we

     * switch between talking to the two participants using a CDMA flash command. Since the network

     * exposes no additional information about the call, the only way we know which caller we're

     * currently talking to is by keeping track of the flash commands that we've sent to the

     * network.

     *

     * For calls that are not generic conferences, or when the generic conference has more than

     * 2 children, returns {@code null}.

     * @see Details#PROPERTY_GENERIC_CONFERENCE