code: public RemixSettings withChannelMappings(AudioChannelMapping... channelMappings) {
          if (this.channelMappings == null) {
              setChannelMappings(new java.util.ArrayList<AudioChannelMapping>(channelMappings.length));
          }
          for (AudioChannelMapping ele : channelMappings) {
              this.channelMappings.add(ele);
          }
          return this;
      }
docs: Mapping of input channels to output channels, with appropriate gain adjustments.
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setChannelMappings(java.util.Collection)} or {@link #withChannelMappings(java.util.Collection)} if you
  want to override the existing values.
  </p>
  
  @param channelMappings
  Mapping of input channels to output channels, with appropriate gain adjustments.
  @return Returns a reference to this object so that method calls can be chained together.