chore: escape backslash in a non-breaking way

Author: diegomarquezp

google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/ClientSideStatementValueConverters.java

@@ -272,9 +272,11 @@ public PgDurationConverter(String allowedValues) {
   /** Converter from string to possible values for read only staleness ({@link TimestampBound}). */
   static class ReadOnlyStalenessConverter
       implements ClientSideStatementValueConverter<TimestampBound> {
+    // We escape a couple of occurrences with the hex code due to
+    // https://github.com/google/google-java-format/issues/1253
     static final ReadOnlyStalenessConverter INSTANCE =
         new ReadOnlyStalenessConverter(
-            "'((STRONG)|(MIN_READ_TIMESTAMP)[\\t ]+((\\d{4})-(\\d{2})-(\\d{2})([Tt](\\d{2}):(\\d{2}):(\\d{2})(\\.\\d{1,9})?)([Zz]|([+-])(\\d{2}):(\\d{2})))|(READ_TIMESTAMP)[\\t ]+((\\d{4})-(\\d{2})-(\\d{2})([Tt](\\d{2}):(\\d{2}):(\\d{2})(\\.\\d{1,9})?)([Zz]|([+-])(\\d{2}):(\\d{2})))|(MAX_STALENESS)[\\t ]+((\\d{1,19})(s|ms|us|ns))|(EXACT_STALENESS)[\\t ]+((\\d{1,19})(s|ms|us|ns)))'");
+            "'((STRONG)|(MIN_READ_TIMESTAMP)[\\t ]+((\\d{4})-(\\d{2})-(\\d{2})([Tt](\\d{2}):(\\d{2}):(\\d{2})(\\.\\d{1,9})?)([Zz]|([+-])(\\d{2}):(\\d{2})))|(READ_TIMESTAMP)[\u005Ct ]+((\\d{4})-(\\d{2})-(\\d{2})([Tt](\\d{2}):(\\d{2}):(\\d{2})(\\.\\d{1,9})?)([Zz]|([+-])(\\d{2}):(\\d{2})))|(MAX_STALENESS)[\u005Ct ]+((\\d{1,19})(s|ms|us|ns))|(EXACT_STALENESS)[\\t ]+((\\d{1,19})(s|ms|us|ns)))'");
 
     private final Pattern allowedValues;
     private final CaseInsensitiveEnumMap<Mode> values = new CaseInsensitiveEnumMap<>(Mode.class);