gnodet commented on code in PR #12540:
URL: https://github.com/apache/maven/pull/12540#discussion_r3651354954
##########
src/mdo/java/ImmutableCollections.java:
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@@ -120,6 +120,12 @@ static <K, V> Map<K, V> copy(Map<K, V> map) {
Map.Entry<K, V> entry = map.entrySet().iterator().next();
return singletonMap(entry.getKey(), entry.getValue());
default:
+ // Check if this is already an immutable JDK map (from
Map.of(), Map.copyOf(), etc.)
+ // Those throw UnsupportedOperationException on put() and
don't need copying
+ String className = map.getClass().getName();
+ if
(className.startsWith("java.util.ImmutableCollections$")) {
Review Comment:
Good catch — the JDK internal class names are indeed not guaranteed and
could change between versions. Rather than switching to a mutation-based test
(try/catch on `put()` has its own downsides: performance overhead on the hot
path, reliance on exception semantics), I've simply removed the check entirely.
In practice, JDK `Map.of()`/`Map.copyOf()` maps rarely appear in the model
builder — most maps are either our own `AbstractImmutableMap` (already
short-circuited) or `HashMap` from merging. The wrapping cost for the
occasional JDK immutable map is a single array copy of the entries, which is
negligible.
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