private void cumulateContent(ChannelHandlerContext ctx, HttpContent msg) {
        cumulation = cumulator.cumulate(ctx.alloc(), cumulation, msg.content());
    }
Adds the current {@link HttpContent} to the cumulation of data.

@param ctx Channel context.
@param msg Current {@link HttpContent} message.
aws-java-sdk-kinesisvideo/src/main/java/com/amazonaws/services/kinesisvideo/internal/netty/handler/ErrorUnmarshallingHandler.java