fix another valid PMD complain

git-svn-id: https://josm.openstreetmap.de/svn/trunk@19299 0c6e7542-c601-0410-84e7-c038aed88b3b

Author: stoecker

src/org/openstreetmap/josm/data/SystemOfMeasurement.java

@@ -304,7 +304,7 @@ public static SystemOfMeasurement getDefault() {
                 .map(LanguageInfo::getLocale)
                 .orElse(Locale.getDefault())
                 .getCountry();
-        if (country == "US")
+        if ("US".equals(country))
             // https://en.wikipedia.org/wiki/Metrication_in_the_United_States#Current_use
             // Imperial units still used in transportation and Earth sciences
             return IMPERIAL;