I found it! If you are looking for a Java method, start exploring under the "Java/" category.
I was fooled by the fact the interface "java(x).sql.DataSource was not under the Java category. But I tried to focus on my implementation (spring app in tomcat) to get the proper implementation package and it was there!
So going forward a nice enhancement would be to show that full package name as a tooltip or something when viewing that method call on other charts.