RFR: 8037573: Typo in DefaultTreeModel docs: askAllowsChildren instead of asksAllowsChildren

[Prasanta Sadhukhan]

[DefaultTreeModel.html#isLeaf](https://docs.oracle.com/en/java/javase/17/docs/api/java.desktop/javax/swing/tree/DefaultTreeModel.html#isLeaf(java.lang.Object)) to an "askAllowsChildren" attribute that doesn't exist. The real attribute is "asksAllowsChildren".
Fixed the typo

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Commit messages:
 - 8037573: Typo in DefaultTreeModel docs: askAllowsChildren instead of asksAllowsChildren

Changes: https://git.openjdk.java.net/jdk/pull/7489/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7489&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8037573
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7489.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7489/head:pull/7489

PR: https://git.openjdk.java.net/jdk/pull/7489