Fix compilation issue

Author: ymohdriz

modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/OpenAPIDeserializer.java

@@ -2712,7 +2712,6 @@ protected static class ParseResult {
         private Map<Location, JsonNode> extra = new LinkedHashMap<>();
         private Map<Location, JsonNode> unsupported = new LinkedHashMap<>();
         private Map<Location, String> invalidType = new LinkedHashMap<>();
-        private List<Location> warnings = new ArrayList<>();
         private List<Location> missing = new ArrayList<>();
 
         public ParseResult() {
@@ -2730,10 +2729,6 @@ public void missing(String location, String key) {
             missing.add(new Location(location, key));
         }
 
-        public void warning(String location, String key) {
-            warnings.add(new Location(location, key));
-        }
-
         public void invalidType(String location, String key, String expectedType, JsonNode value) {
             invalidType.put(new Location(location, key), expectedType);
         }
@@ -2763,11 +2758,6 @@ public List<String> getMessages() {
                 String message = "attribute " + location + l.key + " is missing";
                 messages.add(message);
             }
-            for (Location l : warnings) {
-                String location = l.location.equals("") ? "" : l.location + ".";
-                String message = "attribute " + location +l.key;
-                messages.add(message);
-            }
             for (Location l : unsupported.keySet()) {
                 String location = l.location.equals("") ? "" : l.location + ".";
                 String message = "attribute " + location + l.key + " is unsupported";