runtime(java): Exclude lambda expressions from _when_ _switch-case_ label clauses (#14945)

These guard clauses are always boolean expressions, whereas
lambda expressions can only appear in either an assignment,
a casting, or an invocation context.

References:
https://docs.oracle.com/javase/specs/jls/se21/html/jls-14.html#jls-14.11.1
https://docs.oracle.com/javase/specs/jls/se21/html/jls-15.html#jls-15.27

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/syntax/java.vim b/runtime/syntax/java.vim
index 5ba724d..f5910a8 100644
--- a/runtime/syntax/java.vim
+++ b/runtime/syntax/java.vim
@@ -3,7 +3,7 @@
 " Maintainer:		Aliaksei Budavei <0x000c70 AT gmail DOT com>
 " Former Maintainer:	Claudio Fleiner <claudio@fleiner.com>
 " Repository:		https://github.com/zzzyxwvut/java-vim.git
-" Last Change:		2024 May 30
+" Last Change:		2024 Jun 08
 
 " Please check :help java.vim for comments on some of the options available.
 
@@ -215,7 +215,7 @@
 syn keyword javaLabelCastType	contained char byte short int
 " Allow for the contingency of the enclosing region not being able to
 " _keep_ its _end_, e.g. case ':':.
-syn region  javaLabelWhenClause	contained transparent matchgroup=javaLabel start="\<when\>" matchgroup=NONE end=":"me=e-1 end="->"me=e-2 contains=TOP,javaExternal
+syn region  javaLabelWhenClause	contained transparent matchgroup=javaLabel start="\<when\>" matchgroup=NONE end=":"me=e-1 end="->"me=e-2 contains=TOP,javaExternal,javaLambdaDef
 syn match   javaLabelNumber	contained "\<0\>[lL]\@!"
 syn match   javaLabelNumber	contained "\<\%(0\%([xX]\x\%(_*\x\)*\|_*\o\%(_*\o\)*\|[bB][01]\%(_*[01]\)*\)\|[1-9]\%(_*\d\)*\)\>[lL]\@!"
 hi def link javaLabelDefault	javaLabel