Fix RefToken equals/hashCode to include semantic identity (index and keyRef fields)

[coderabbitai]

Description

The RefToken class has a semantic bug in its equals() and hashCode() implementations. Currently, these methods only consider the decodedToken field, ignoring the index and keyRef fields. This causes semantically different tokens to be incorrectly treated as equal.

Problem

Two RefToken instances can have the same decodedToken but represent different operations:

• append("0") creates RefToken("0", null, null) — field access
• append(0) creates RefToken("0", 0, null) — array index access

The current implementation would incorrectly consider these tokens equal, which can cause AbstractJsonPointer.equals() to fail when comparing paths that differ in semantic type (e.g., /a/0/b where the 0 is a field name vs. an array index).

Expected Behavior

The equals() method should compare all three fields: decodedToken, index, and keyRef using null-safe comparisons (e.g., Objects.equals).

The hashCode() method should include all three fields (e.g., Objects.hash(decodedToken, index, keyRef)).

Additional Context

This is a pre-existing issue from the original JsonPointer implementation where RefToken was an inner class. It was identified during PR #221 (Jackson 3.x support) when RefToken was extracted to a standalone class.

Reference:

• PR: Add Jackson 3 support #221
• Discussion: Add Jackson 3 support #221 (comment)

Reported by: @sondemar

Location

src/main/java/com/flipkart/zjsonpatch/RefToken.java lines 121-134