StringUtils.parseLocaleString accepts Java 7 variants

Issue: SPR-14718

spring-core/src/main/java/org/springframework/util/StringUtils.java

@@ -715,7 +715,7 @@ public abstract class StringUtils {
 	private static void validateLocalePart(String localePart) {
 		for (int i = 0; i < localePart.length(); i++) {
 			char ch = localePart.charAt(i);
-			if (ch != '_' && ch != ' ' && !Character.isLetterOrDigit(ch)) {
+			if (ch != ' ' && ch != '_' && ch != '#' && !Character.isLetterOrDigit(ch)) {
 				throw new IllegalArgumentException(
 						"Locale part \"" + localePart + "\" contains invalid characters");
 			}

spring-core/src/test/java/org/springframework/util/StringUtilsTests.java

@@ -692,4 +692,9 @@ public class StringUtilsTests {
 		assertEquals("Variant containing country code not extracted correctly", variant, locale.getVariant());
 	}
 
+	@Test  // SPR-14718
+	public void testParseJava7Variant() {
+		assertEquals("sr_#LATN", StringUtils.parseLocaleString("sr_#LATN").toString());
+	}
+
 }