RFR: JDK-8229386 Typo "lables" in doc comment

[Jonathan Gibbons]

Please review a trivial fix for a typo in a doc comment.  What should be 
"labels" is incorrectly spelt as "lables".

-- Jon

JBS: https://bugs.openjdk.java.net/browse/JDK-8229386

Patch:

$ hg diff -R open
diff -r 072f27397b69 
src/jdk.compiler/share/classes/com/sun/source/tree/CaseTree.java
--- a/src/jdk.compiler/share/classes/com/sun/source/tree/CaseTree.java 
Fri Aug 09 12:27:05 2019 -0700
+++ b/src/jdk.compiler/share/classes/com/sun/source/tree/CaseTree.java 
Fri Aug 09 15:00:41 2019 -0700
@@ -49,7 +49,7 @@
      /**
       * Returns the expression for the case, or
       * {@code null} if this is the default case.
- * If this case has multiple lables, returns the first label.
+ * If this case has multiple labels, returns the first label.
       * @return the expression for the case, or null
       */
      ExpressionTree getExpression();