runtime(java): Manage byte limits for variable-width lookbehind assertions

Raise the byte limits from 80 to 120 for "javaFuncDef" and
"java*CommentTitle"; and support selecting other arbitrary
values with
------------------------------------------------------------
	let g:java_lookbehind_byte_counts = {
		\ 'javaMarkdownCommentTitle': 240,
	\ }
------------------------------------------------------------

for related groups of syntax definitions, referring to their
names with dictionary keys.

Over-80-Byte-Limit Lookbehind Examples:
https://raw.githubusercontent.com/openjdk/jdk/refs/tags/jdk-24%2B36/src/java.base/share/classes/sun/security/x509/NamedX509Key.java [Lines 43 & 44]
https://raw.githubusercontent.com/openjdk/jdk/refs/tags/jdk-24%2B36/src/jdk.compiler/share/classes/com/sun/tools/javac/util/GraphUtils.java [Line 154]

closes: #17921

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: zzzyxwvut

runtime/doc/syntax.txt

@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2025 Aug 07
+*syntax.txt*	For Vim version 9.1.  Last change: 2025 Aug 08
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -2231,6 +2231,15 @@ Certain modifiers are incompatible with each other, e.g. `abstract` and
 and can be differently highlighted as a group than other modifiers with >
 	:hi link javaConceptKind NonText
 
+All instances of variable-width lookbehind assertions (|/\@<!| and |/\@<=|),
+resorted to in syntax item definitions, are confined to arbitrary byte counts.
+Another arbitrary value can be selected for a related group of definitions.
+For example: >
+	:let g:java_lookbehind_byte_counts = {'javaMarkdownCommentTitle': 240}
+Where each key name of this dictionary is the name of a syntax item.  The use
+of these assertions in syntax items may vary among revisions, so no definitive
+set of supported key names is committed to.
+
 If you notice highlighting errors while scrolling backwards, which are fixed
 when redrawing with CTRL-L, try setting the "g:java_minlines" variable to
 a larger number: >

runtime/syntax/java.vim

@@ -1,9 +1,9 @@
 | +0#0000e05#a8a8a8255@1>/+0&#ffffff0@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |s|e|t|l|o|c|a|l| |f|o|l|d|e|n|a|b|l|e| |f|o|l|d|c|o|l|u|m|n|=|2| |f|o|l|d|m|e|t|h|o|d|=|s|y|n|t|a|x| +0#0000000&@4
 | +0#0000e05#a8a8a8255@1|/+0&#ffffff0@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |l|e|t| |g|:|j|a|v|a|_|f|o|l|d|t|e|x|t|_|s|h|o|w|_|f|i|r|s|t|_|o|r|_|s|e|c|o|n|d|_|l|i|n|e| |=| |1| +0#0000000&@5
+| +0#0000e05#a8a8a8255@1|/+0&#ffffff0@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |l|e|t| |g|:|j|a|v|a|_|l|o@1|k|b|e|h|i|n|d|_|b|y|t|e|_|c|o|u|n|t|s| |=| |{|'|j|a|v|a|B|l|o|c|k|'|:| |-|1|}| +0#0000000&@1
 | +0#0000e05#a8a8a8255@1|/+0&#ffffff0@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |h|i|g|h|l|i|g|h|t| |l|i|n|k| |j|a|v|a|B|l|o|c|k|O|t|h|e|r|S|t|a|r|t| |S|t|r|u|c|t|u|r|e| +0#0000000&@10
 | +0#0000e05#a8a8a8255@1|/+0&#ffffff0@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |h|i|g|h|l|i|g|h|t| |l|i|n|k| |j|a|v|a|B|l|o|c|k|S|t|a|r|t| |T|o|d|o| +0#0000000&@20
 | +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@72
-| +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@72
 |++0#0000e05#a8a8a8255| |+|-@1| |1|9| |l|i|n|e|s|:| |@|S|u|p@1|r|e|s@1|W|a|r|n|i|n|g|s|(|{|-@39
 | @1|c+0#00e0003#ffffff0|l|a|s@1| +0#0000000&|F|o|l|d|i|n|g|T|e|s|t|s| |{+0#00e0003&| +0#0000000&@52
 | +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@3|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|F|o|l|d|e|n|a|b|l|e| @48

runtime/syntax/testdir/dumps/java_enfoldment_00.dump

@@ -15,6 +15,6 @@
 | +0#0000e05#a8a8a8255@1|/+0&#ffffff0@1| |{| +0#0000000&@68
 | +0#0000e05#a8a8a8255@1|/+0&#ffffff0@1| |}| +0#0000000&@68
 | +0#0000e05#a8a8a8255@1| +0#0000000#ffffff0@72
-|++0#0000e05#a8a8a8255| |+|-@1| @1|2| |l|i|n|e|s|:| |1|2@1|||.@54
-|~+0#4040ff13#ffffff0| @73
-| +0#0000000&@56|9|7|,|2|-|1| @7|B|o|t| 
+| +0#0000e05#a8a8a8255@1|/+0&#ffffff0|*| |1|2@1|||.@65
+| +0&#a8a8a8255@1|.+0&#ffffff0@23|*|/| +0#0000000&|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|F|o|l|d|e|n|a|b|l|e| |{+0#00e0003&| +0#0000000&@23
+@57|9|7|,|2|-|1| @7|9|8|%| 

runtime/syntax/testdir/dumps/java_enfoldment_02.dump

@@ -0,0 +1,20 @@
+| +0#0000e05#a8a8a8255@1|/+0&#ffffff0|*| |1|2@1|||.@65
+| +0&#a8a8a8255@1|.+0&#ffffff0@23|*|/| +0#0000000&|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|F|o|l|d|e|n|a|b|l|e| |{+0#00e0003&| +0#0000000&@23
+| +0#0000e05#a8a8a8255@1>}+0#00e0003#ffffff0| +0#0000000&@71
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+| +0#0000000&@56|1|2@1|,|1| @8|B|o|t| 

runtime/syntax/testdir/dumps/java_enfoldment_03.dump

@@ -1,9 +1,9 @@
 >/+0#0000e05#ffffff0@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |s|e|t|l|o|c|a|l| |n|o|f|o|l|d|e|n|a|b|l|e| +0#0000000&@35
 |/+0#0000e05&@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |l|e|t| |g|:|j|a|v|a|_|m|a|r|k|_|b|r|a|c|e|s|_|i|n|_|p|a|r|e|n|s|_|a|s|_|e|r@1|o|r|s| |=| |1| +0#0000000&@10
+|/+0#0000e05&@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |l|e|t| |g|:|j|a|v|a|_|l|o@1|k|b|e|h|i|n|d|_|b|y|t|e|_|c|o|u|n|t|s| |=| |{|'|j|a|v|a|B|l|o|c|k|'|:| |-|1|}| +0#0000000&@3
 |/+0#0000e05&@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |h|i|g|h|l|i|g|h|t| |l|i|n|k| |j|a|v|a|B|l|o|c|k|O|t|h|e|r|S|t|a|r|t| |S|t|r|u|c|t|u|r|e| +0#0000000&@12
 |/+0#0000e05&@1| |V|I|M|_|T|E|S|T|_|S|E|T|U|P| |h|i|g|h|l|i|g|h|t| |l|i|n|k| |j|a|v|a|B|l|o|c|k|S|t|a|r|t| |T|o|d|o| +0#0000000&@22
 @75
-@75
 @4|@+0#e000e06&|S|u|p@1|r|e|s@1|W|a|r|n|i|n|g|s|(|{+0#0000001#ffff4012| +0#0000000#ffffff0@51
 @4|"@2| @67
 | +0#e000002&@3|b|e|s|p|o|k|e| +0#0000000&@63

runtime/syntax/testdir/dumps/java_unfoldment_00.dump

@@ -16,5 +16,5 @@
 |/+0#0000e05&@1| |}| +0#0000000&@70
 @75
 |/+0#0000e05&|*| |1|2@1|||.@67
-@20|*|/| +0#0000000&|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|U|n|f|o|l|d|e|n|a|b|l|e| |{+0#0000001#ffff4012| +0#0000000#ffffff0@27
+@20|*|/| +0#0000000&|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|U|n|f|o|l|d|e|n|a|b|l|e| |{+0#00e0003&| +0#0000000&@27
 @57|1|0|9|,|1| @8|9@1|%| 

runtime/syntax/testdir/dumps/java_unfoldment_06.dump

@@ -1,6 +1,6 @@
 |/+0#0000e05#ffffff0|*| |1|2@1|||.@67
-@20|*|/| +0#0000000&|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|U|n|f|o|l|d|e|n|a|b|l|e| |{+0#0000001#ffff4012| +0#0000000#ffffff0@27
->}+0#0000001#ffff4012| +0#0000000#ffffff0@73
+@20|*|/| +0#0000000&|i+0#00e0003&|n|t|e|r|f|a|c|e| +0#0000000&|U|n|f|o|l|d|e|n|a|b|l|e| |{+0#00e0003&| +0#0000000&@27
+>}+0#00e0003&| +0#0000000&@73
 |~+0#4040ff13&| @73
 |~| @73
 |~| @73

runtime/syntax/testdir/dumps/java_unfoldment_07.dump

@@ -1,9 +1,9 @@
 // VIM_TEST_SETUP setlocal foldenable foldcolumn=2 foldmethod=syntax
 // VIM_TEST_SETUP let g:java_foldtext_show_first_or_second_line = 1
+// VIM_TEST_SETUP let g:java_lookbehind_byte_counts = {'javaBlock': -1}
 // VIM_TEST_SETUP highlight link javaBlockOtherStart Structure
 // VIM_TEST_SETUP highlight link javaBlockStart Todo
 
-
 	@SuppressWarnings({
 	"""
 	bespoke

runtime/syntax/testdir/input/java_enfoldment.java

@@ -1,9 +1,9 @@
 // VIM_TEST_SETUP setlocal nofoldenable
 // VIM_TEST_SETUP let g:java_mark_braces_in_parens_as_errors = 1
+// VIM_TEST_SETUP let g:java_lookbehind_byte_counts = {'javaBlock': -1}
 // VIM_TEST_SETUP highlight link javaBlockOtherStart Structure
 // VIM_TEST_SETUP highlight link javaBlockStart Todo
 
-
 	@SuppressWarnings({
 	"""
 	bespoke