RFR: 4756278: RFE: Insufficient API documentation for java.awt.Polygon constructor

[SWinxy]

Appends: `, copying the array contents of {@code xpoints} and {@code ypoints}` to specify that the arrays in the constructor are explicitly copied.

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Commit messages:
 - 4756278: RFE: Insufficient API documentation for java.awt.Polygon constructor

Changes: https://git.openjdk.org/jdk/pull/10418/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10418&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-4756278
  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/10418.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10418/head:pull/10418

PR: https://git.openjdk.org/jdk/pull/10418