code: public void setChannelMappings(java.util.Collection<AudioChannelMapping> channelMappings) {
          if (channelMappings == null) {
              this.channelMappings = null;
              return;
          }
  
          this.channelMappings = new java.util.ArrayList<AudioChannelMapping>(channelMappings);
      }
docs: Mapping of input channels to output channels, with appropriate gain adjustments.
  
  @param channelMappings
  Mapping of input channels to output channels, with appropriate gain adjustments.