public interface TestClient {
        @Get(url = "/data/", contentType = "application/{json}")
        String contentTypeVar();
    }

com.dtflys.forest.exceptions.ForestVariableUndefinedException: [Forest] Cannot resolve variable 'json'

	[From Template]
	method: com.dtflys.test.exception.TestExceptions$TestClient.contentTypeVar()
	annotation: com.dtflys.forest.annotation.@Get
	attribute: contentType = "application/{json}"

	at com.dtflys.forest.mapping.MappingTemplate.render(MappingTemplate.java:496)
	at com.dtflys.forest.reflection.ForestMethod.makeRequest(ForestMethod.java:834)
	at com.dtflys.forest.reflection.ForestMethod.invoke(ForestMethod.java:1351)
	at com.dtflys.forest.proxy.InterfaceProxyHandler.invoke(InterfaceProxyHandler.java:223)
	at com.sun.proxy.$Proxy25.contentTypeVar(Unknown Source)
        ... ...