Method equals

src/main/java/groovy/util/Expando.java:164–175

This allows equals to be overridden by a closure field method attached to the expando object. @see java.lang.Object#equals(java.lang.Object)

(Object obj)

     * @see java.lang.Object#equals(java.lang.Object)
     */
    @Override
    public boolean equals(Object obj) {
        Object method = getProperties().get("equals");
        if (method instanceof Closure closure) {
            // invoke overridden equals closure method
            closure.setDelegate(this);
            Boolean ret = (Boolean) closure.call(obj);
            return ret;
        } else {
            return super.equals(obj);
        }
    }

    /**
     * This allows hashCode to be overridden by a closure <i>field</i> method attached