kemitix-checkstyle-ruleset/builder/src/main/resources/rules/AvoidEscapedUnicodeCharacters.md

Prevents use of obscure escape codes (e.g. \u221e). However, non-printable/control characters are still permitted.

Valid:

String unitAbbrev = "??s";
String byteOrdered = '\ufeff' = content;

Invalid:

String unitAbbrev = "\u03bcs";