Filters seem to not do anything?

When I run the following snippet…

REFLECTIONS = new Reflections(
	            new ConfigurationBuilder()
	            .setUrls(ClasspathHelper.forJavaClassPath())
	            .setScanners(new SubTypesScanner(true))
	            .filterInputsBy(
	                    new FilterBuilder()
	                    .excludePackage("java.")
	                    .excludePackage("javax.")
	                    .add((s) -> {return s.contains(".class");}))
	            );

…I get inter alia the following errors from reflections…

org.reflections.ReflectionsException: could not create class object from file ch/qos/logback/classic/gaffer/ConfigurationDelegate.groovy
	at org.reflections.scanners.AbstractScanner.scan(AbstractScanner.java:32)
	at org.reflections.Reflections.scan(Reflections.java:253)
	at org.reflections.Reflections.scan(Reflections.java:202)
	at org.reflections.Reflections.<init>(Reflections.java:123)

...

08:12:57.154 [main] DEBUG org.reflections.Reflections - expanded subtype java.io.OutputStream -> java.io.ByteArrayOutputStream

...

08:12:57.167 [main] WARN  org.reflections.Reflections - could not get type for name javax.servlet.ServletContextListener from any class loader
org.reflections.ReflectionsException: could not get type for name javax.servlet.ServletContextListener
	at org.reflections.ReflectionUtils.forName(ReflectionUtils.java:390)
	at org.reflections.Reflections.expandSuperTypes(Reflections.java:381)
	at org.reflections.Reflections.<init>(Reflections.java:126)

…even though I’ve added filters & predicates to remove files that aren’t classe, as well as the java and javax packages!

Is it me misunderstanding/doing something wrong, or is this an actual bug?

[ts14ic]

p.s. Initially I thought the problem was caused by FilterBuilder using a somewhat inconsistent combination of OR and AND semantics (sometimes the filter is incremental, sometimes it’s not).

A combination of include + exclude includes all classes allowed by first predicate and then excludes the remaining ones using the second predicate. An AND semantic is implied (the filter is incremental). The class is included only if it passes both filters. Looks ok.

A combination of exclude + exclude uses the AND semantic as well (the filter is incremental). A class is included only if it passes both filters

But a combination of include + include is using the OR semantic - a class is allowed if any of the predicates pass. The filter is not incremental here.

Say, I’m using includePackage("foo") and include(".*BarClass").
I’d expect only foo....BarClass to be included, but it actually includes anything that has the package foo OR has the BarClass ending.

I can create a separate issue 😃.

[ts14ic]

The behavior in OP is likely caused by configurationBuilder.setExpandSuperTypes(true) set by default. The stacktraces contain expandSuperTypes.
Explicitly calling setExpandSuperTypes(false) will help.

Also, it seems that expandSuperTypes is applied AFTER filters.