Regex used to parse Grok patterns prints warning with latest Joni

[droberts195]

Following the Joni upgrade in #47374 the following warning is printed on Elasticsearch startup:

regular expression has redundant nested repeat operator + /%\{(?<name>(?<pattern>[A-z0-9]+)(?::(?<subname>[[:alnum:]@\[\]_:.-]+))?)(?:=(?<definition>(?:(?:[^{}]+|\.+)+)+))?\}/

I guess it means there is a non-fatal inefficiency in this regex:

elasticsearch/libs/grok/src/main/java/org/elasticsearch/grok/Grok.java

Lines 50 to 63 in f6f249b

	private static final String GROK_PATTERN =
	"%\\{" +
	"(?<name>" +
	"(?<pattern>[A-z0-9]+)" +
	"(?::(?<subname>[[:alnum:]@\\[\\]_:.-]+))?" +
	")" +
	"(?:=(?<definition>" +
	"(?:" +
	"(?:[^{}]+|\\.+)+" +
	")+" +
	")" +
	")?" + "\\}";
	private static final Regex GROK_PATTERN_REGEX = new Regex(GROK_PATTERN.getBytes(StandardCharsets.UTF_8), 0,
	GROK_PATTERN.getBytes(StandardCharsets.UTF_8).length, Option.NONE, UTF8Encoding.INSTANCE, Syntax.DEFAULT);

That regular expression has not changed for a long time, so fixing it is probably not necessary for correctness, but it will avoid questions on forums/issues/support cases if it could be fixed before release of 7.5.

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/Ingest)