RFR: JDK-8170945: Collectors$Partition should override more Map methods

[Alan Bateman]

On Wed, 5 Apr 2023 09:19:57 GMT, Viktor Klang <duke at openjdk.org> wrote:

> Adds overrides for common Map operations to avoid having to allocate the entrySet for Collectors$Partition maps.

src/java.base/share/classes/java/util/stream/Collectors.java line 1988:

> 1986:         public T get(Object key) {
> 1987:             if (key instanceof Boolean b) {
> 1988:                 return b.booleanValue() ? forTrue : forFalse;

Usages of partitioningBy are likely to be followed by get(TRUE) and get(FALSE) to get the sets in each partition, so this looks good, avoids needing the entrySet and and iterator.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13347#discussion_r1158336071