[MNG-8178] Fall back to system properties for missing profile activat…

…ion context properties (#1603)

A call to context.getSystemProperties() may yield empty an empty map, or
one missing the desired key, which makes a subsequent call of
toLowerCase fail with a NullPointerException.

Fall-back to using Os.OS_NAME and similar properties.

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Co-authored-by: Guillaume Nodet <gnodet@gmail.com>

maven-model-builder/src/main/java/org/apache/maven/model/profile/activation/OperatingSystemProfileActivator.java

@@ -58,9 +58,15 @@ public boolean isActive(Profile profile, ProfileActivationContext context, Model
 
         boolean active = ensureAtLeastOneNonNull(os);
 
-        String actualOsName = context.getSystemProperties().get("os.name").toLowerCase(Locale.ENGLISH);
-        String actualOsArch = context.getSystemProperties().get("os.arch").toLowerCase(Locale.ENGLISH);
-        String actualOsVersion = context.getSystemProperties().get("os.version").toLowerCase(Locale.ENGLISH);
+        String actualOsName = context.getSystemProperties()
+                .getOrDefault("os.name", Os.OS_NAME)
+                .toLowerCase(Locale.ENGLISH);
+        String actualOsArch = context.getSystemProperties()
+                .getOrDefault("os.arch", Os.OS_ARCH)
+                .toLowerCase(Locale.ENGLISH);
+        String actualOsVersion = context.getSystemProperties()
+                .getOrDefault("os.version", Os.OS_VERSION)
+                .toLowerCase(Locale.ENGLISH);
 
         if (active && os.getFamily() != null) {
             active = determineFamilyMatch(os.getFamily(), actualOsName);