Fix Version constructor from string

Author: sbernard31

leshan-core/src/main/java/org/eclipse/leshan/core/LwM2m.java

@@ -144,20 +144,25 @@ public static Version getDefault() {
         public static String validate(String version) {
             if (version == null || version.isEmpty())
                 return "version MUST NOT be null or empty";
-            String[] versionPart = version.split("\\.");
-            if (versionPart.length != 2) {
+            // We use split with limit = -1 to be sure "split" will discard trailing empty strings
+            String[] versionParts = version.split("\\.", -1);
+            if (versionParts.length != 2) {
                 return String.format("version (%s) MUST be composed of 2 parts", version);
             }
             for (int i = 0; i < 2; i++) {
+                String versionPart = versionParts[i];
                 try {
-                    short parsedShort = Short.parseShort(versionPart[i]);
+                    if (versionPart.length() > 1 && versionPart.startsWith("0")) {
+                        return String.format("version (%s) part %d (%s) must not be prefixed by 0", version, i + 1,
+                                versionPart);
+                    }
+                    short parsedShort = Short.parseShort(versionPart);
                     if (parsedShort < 0) {
                         return String.format("version (%s) part %d (%s) must not be negative", version, i + 1,
-                                versionPart[i]);
+                                versionPart);
                     }
                 } catch (Exception e) {
-                    return String.format("version (%s) part %d (%s) is not a valid short", version, i + 1,
-                            versionPart[i]);
+                    return String.format("version (%s) part %d (%s) is not a valid short", version, i + 1, versionPart);
                 }
             }
             return null;

leshan-core/src/test/java/org/eclipse/leshan/core/VersionTest.java

@@ -85,6 +85,9 @@ private static Stream<Arguments> illegal_arguments() {
         return Stream.of(args(() -> new Version(null), "version MUST NOT be null or empty"),
                 args(() -> new Version(""), "version MUST NOT be null or empty"),
                 args(() -> new Version("foo"), "version (foo) MUST be composed of 2 parts"),
+                args(() -> new Version("0001.0"), "version (0001.0) part 1 (0001) must not be prefixed by 0"),
+                args(() -> new Version("1.02"), "version (1.02) part 2 (02) must not be prefixed by 0"),
+                args(() -> new Version("1.0."), "version (1.0.) MUST be composed of 2 parts"),
                 args(() -> new Version("1.0.0"), "version (1.0.0) MUST be composed of 2 parts"),
                 args(() -> new Version("-1.0"), "version (-1.0) part 1 (-1) must not be negative"),
                 args(() -> new Version("1.-1"), "version (1.-1) part 2 (-1) must not be negative"),