code: protected void makeInternalLink(APMSpanBuilder builder) {
          getNodeBuilder().setNodeType(NodeType.Consumer);
          getNodeBuilder().setEndpointType(null);
  
          EndpointRef epref = getTraceContext().getSourceEndpoint();
          getNodeBuilder().setUri(epref.getUri());
          getNodeBuilder().setOperation(epref.getOperation());
  
          getNodeBuilder().setTimestamp(TimeUtil.toMicros(builder.start));
  
          // Create new node builder for the actual span, as a child of the 'Consumer' that
          // is providing the link back to the referenced node
          nodeBuilder = new NodeBuilder(getNodeBuilder());
      }
docs: This method creates a Consumer node to link the new trace fragment to a
  node associated with a referenced Span. This method sets the type of
  the current node to be Consumer, initialises its URI/Operation to the
  endpoint details of the supplied trace context, and then creates a new
  child node upon which subsequent configuration will be performed.
  
  @param builder The span builder