Extend allowed characters for grok field names
@@ -52,7 +52,7 @@ public final class Grok {
"%\\{" +
"(?<name>" +
"(?<pattern>[A-z0-9]+)" +
- "(?::(?<subname>[A-z0-9_:.-]+))?" +
+ "(?::(?<subname>[[:alnum:]@\\[\\]_:.-]+))?" +
")" +
"(?:=(?<definition>" +
"(?:" +
