• Fixes duplicate field name handling in InstanceCoercer#getFieldWriters
• Adds merge function to Collectors.toMap() to retain first entry
• Uses LinkedHashMap to preserve field processing order
• Prevents runtime IllegalStateException on duplicate keys

Add merge function and LinkedHashMap to toMap collector

• Modified Collectors.toMap() call to include merge function (existing, ignored) -> existing
• Added LinkedHashMap::new as map supplier to preserve insertion order
• Prevents IllegalStateException: Duplicate key when multiple fields resolve to same serialized
 name
• Retains first discovered field writer and ignores subsequent duplicates

java/src/org/openqa/selenium/json/InstanceCoercer.java

Description

The change alters runtime behavior for duplicate field names (now silently keeping the first writer)
without adding a unit test to prevent regressions. This makes it easy for future refactors to
reintroduce duplicate-key failures or change which field “wins” without detection.

Code

java/src/org/openqa/selenium/json/InstanceCoercer.java[R129-131]

+                },
+                (existing, ignored) -> existing,
+                java.util.LinkedHashMap::new));

Evidence

PR Compliance ID 4 requires adding/updating tests for behavior changes where feasible. The updated
collector explicitly changes behavior on duplicate keys, and the PR itself notes tests as follow-up
work rather than including them.

AGENTS.md
java/src/org/openqa/selenium/json/InstanceCoercer.java[129-131]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
`InstanceCoercer#getFieldWriters` now retains the first writer when duplicate field names occur, but this behavior change is not covered by tests.
## Issue Context
Duplicate field names can happen via field hiding (same-named fields across a class hierarchy). Historically this could throw `Duplicate key` during collection; now duplicates are ignored. This should be locked in with a unit test to prevent regressions and to ensure deterministic "winner" behavior.
## Fix Focus Areas
- java/src/org/openqa/selenium/json/InstanceCoercer.java[99-132]
- java/test/org/openqa/selenium/json/JsonTest.java[113-145]

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

Description

getFieldWriters now silently ignores later fields that resolve to the same JSON key, which can
hide ambiguous class designs (field hiding) and lead to missing/incorrectly-applied data without any
signal. This trades a clear failure (duplicate key exception) for silent data loss and harder
debugging when duplicates exist.

Code

java/src/org/openqa/selenium/json/InstanceCoercer.java[R129-131]

+                },
+                (existing, ignored) -> existing,
+                java.util.LinkedHashMap::new));

Evidence

Fields are collected starting from the concrete class and then walking up the superclass chain, and
the collector now keeps the first entry and drops subsequent ones for the same key. During
deserialization only the retained writer is used for a given JSON key, so any dropped duplicate
field can never be set, with no warning/error emitted by this code path.

java/src/org/openqa/selenium/json/InstanceCoercer.java[99-105]
java/src/org/openqa/selenium/json/InstanceCoercer.java[107-132]
java/src/org/openqa/selenium/json/InstanceCoercer.java[77-88]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
`InstanceCoercer#getFieldWriters` now resolves duplicate field-name collisions by silently keeping the first writer and ignoring the rest. This can cause silent data loss / surprising field selection when a subclass hides a superclass field, making deserialization bugs very hard to detect.
### Issue Context
The stream collects fields across the class hierarchy and then builds a map keyed by `Field::getName`. With the new merge function, duplicates are no longer surfaced to the caller.
### Fix Focus Areas
- java/src/org/openqa/selenium/json/InstanceCoercer.java[99-132]

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools