if NetworkDiagram is loaded inside Button.ClickListener it throws "java.l

if NetworkDiagram is loaded inside Button.ClickListener it throws

“java.lang.AbstractMethodError: org.vaadin.visjs.networkDiagram.NetworkDiagram$9.call(Lelemental/json/JsonArray;)” exception .

any idea for this problem?

google gson library is used to convert the java objects to json. may be the problem in this conversion. mail me the full stack trace.