Use skipOptionalWhitespaces() instead of explicit loop

Author: catamorphism

Diff for: icu4j/main/core/src/main/java/com/ibm/icu/message2/MFParser.java

@@ -49,14 +49,7 @@ private MFDataModel.Message parseImpl() throws MFParseException {
         // Determine if message is simple or complex; this requires
         // looking through whitespace.
         int savedPosition = input.getPosition();
-        while (true) {
-            int cp = input.peekChar();
-            if (!StringUtils.isWhitespace(cp)) {
-                break;
-            }
-            // Skip past whitespace
-            cp = input.readCodePoint();
-        }
+        skipOptionalWhitespaces();
         int cp = input.peekChar();
         if (cp == '.') { // declarations or .match
             // No need to restore whitespace