in log4j-weaver/src/main/java/org/apache/logging/log4j/weaver/LocationClassConverter.java [48:57]
public void convert(InputStream src, OutputStream dest, LocationCacheGenerator locationCache) throws IOException {
final ClassWriter writer = new PrivateClassWriter(ClassWriter.COMPUTE_FRAMES, classpath);
final LocationClassVisitor converter = new LocationClassVisitor(writer, locationCache);
converter.addClassConversionHandler(new LoggerConversionHandler());
converter.addClassConversionHandler(new LogBuilderConversionHandler());
new ClassReader(src).accept(converter, ClassReader.EXPAND_FRAMES);
dest.write(writer.toByteArray());
}