Fix bug in TestsReader

Use Optional.ofNullable to avoid throwing an NPE when a class file can't be read.

Signed-off-by: Patrick Strawderman <[email protected]>

Author: kilink

plugin/src/main/java/org/gradle/testretry/internal/testsreader/TestsReader.java

@@ -97,7 +97,7 @@ private <R> Optional<R> readClasspathClass(String className, Supplier<? extends
             if (file.isDirectory()) {
                 File classFile = new File(file, classFileName);
                 if (classFile.exists()) {
-                    return Optional.of(visitClassFile(classFile, factory.get()));
+                    return Optional.ofNullable(visitClassFile(classFile, factory.get()));
                 } else {
                     continue;
                 }