typo

Co-authored-by: Marcono1234 <Marcono1234@users.noreply.github.com>

Author: MukjepScarlet

gson/src/main/java/com/google/gson/JsonArray.java

@@ -41,7 +41,7 @@
  * @author Joel Leitch
  */
 public final class JsonArray extends JsonElement implements Iterable<JsonElement> {
-  /** All elements in this list are nonnull. */
+  /** All elements in this list are non-null. */
   private final ArrayList<JsonElement> elements;
 
   @SuppressWarnings({"deprecation", "NonApiType"}) // superclass constructor