User node pointing to a node with same application name but different service type throws an exception

[Xylus]

In relation to issue #214, applications with the same application name can now be selected separately as long as their service types differ.
However, user nodes are generated on the server map taking only the destination's application name into account.

For example, if there are 2 nodes with the same application name but different service type (ie TOMCAT, SPRING-BOOT both named myApp) with 2 USER nodes each pointing to myApp[TOMCAT], and myApp[SPRING-BOOT], the Web UI throws an error when drawing the server map.
This is because the USER node is generated by extracting the application name of the destination node, which in this case would result in only a single USER node being generated.

2 possible solutions exist.

1. Draw only a single USER node that points to both myApp[TOMCAT] and myApp[SPRING-BOOT].
   
2. Draw 2 separate USER nodes each pointing to myApp[TOMCAT] and myApp[SPRING-BOOT].
   

The second solution seems like the better option - but this requires the destination node's service type to already be stored in hbase.