src/main/java/com/github/fge/grappa/transform/load/ReflectiveClassLoader.java
@Nullable
    public Class<?> findClass(final String className)
    {
        Objects.requireNonNull(className);

        try {
            return (Class<?>) findClass.invoke(loader, className);
        } catch (IllegalAccessException | InvocationTargetException e) {
            throw new ParserTransformException("unable to find class by name ("
                + className + ')', e);
        }
    }
@Nullable
    public Class<?> findClass(final String className)
    {
        Objects.requireNonNull(className);

        try {
            return (Class<?>) findClass.invoke(loader, className);
        } catch (IllegalAccessException | InvocationTargetException e) {
            throw new ParserTransformException("unable to find class by name ("
                + className + ')', e);
        }
    }
Returns the class with the given name if it has already been loaded by
the given class loader

<p>If the class has not been loaded yet, this method returns {@code
null}.</p>

@param className the full name of the class to be loaded
@return the class instance, if found