In my project, I have a class that extends ConfigurableSocketFactory, but the setConfiguration method is never called. I added a breakpoint to if (socketFactoryClass.isInstance(ConfigurableSocketFactory.class)) {, and the expression was evaluating to false.

From my googling, I landed at https://stackoverflow.com/questions/31083699/java-class-isinstance-always-returns-false, which indicated that the evaluation was being done backwards.

When I evaluated ConfigurableSocketFactory.class.isInstance(socketFactory), the result was true