code: public ClassInfoList getInterfaces(final String className) {
          if (closed.get()) {
              throw new IllegalArgumentException("Cannot use a ScanResult after it has been closed");
          }
          if (!scanSpec.enableClassInfo) {
              throw new IllegalArgumentException("Please call ClassGraph#enableClassInfo() before #scan()");
          }
          final ClassInfo classInfo = classNameToClassInfo.get(className);
          return classInfo == null ? ClassInfoList.EMPTY_LIST : classInfo.getInterfaces();
      }
docs: Get all interfaces implemented by the named class or by one of its superclasses, if this is a standard class,
  or the superinterfaces extended by this interface, if this is an interface.
  
  @param className
  The class name.
  @return A list of interfaces implemented by the named class (or superinterfaces extended by the named
  interface), or the empty list if none.