@Override
            public boolean equals(Object obj) {
                if (obj == this) {
                    return true;
                }
                if (obj == null || obj.getClass() != this.getClass()) {
                    return false;
                }
                Index that = (Index) obj;
                return this.index == that.index;
            }
A {@link FunctionDefinition} for the {@link GetAttr} function.
smithy-rules-engine/src/main/java/software/amazon/smithy/rulesengine/language/syntax/expressions/functions/GetAttr.java