FU: Fix default env var behavior

Author: PerfectSlayer

components/environment/src/main/java/datadog/environment/EnvironmentVariables.java

@@ -27,7 +27,8 @@ private EnvironmentVariables() {}
    */
   public static String getOrDefault(@Nonnull String name, String defaultValue) {
     try {
-      return System.getenv(name);
+      String value = System.getenv(name);
+      return value == null ? defaultValue : value;
     } catch (SecurityException e) {
       return defaultValue;
     }