I have a road network with streetnames i want to check some gaps in the continuity of the streetnames

You can use a LineCombiner (LineJoiner) grouped by streetname, followed by an Aggregator with the same group by. If the count attribute is greater than one, then you have discontinuous streets.

Because the street is a network which consists of several branches, rather than a single polyline. If you need to determine if the branches exactly connect each other at the nodes (junctions), send them to the NetworkTopologyCalculator (Group By: street name), then check if the network ID (which is generated by the transformer) is unique or not for each street. If there are two or more network IDs for an identical street, there should be gaps at some nodes.