SPIGOT-4758: --server-port argument does not work

By: md_5 <git@md-5.net>

paper-server/nms-patches/PropertyManager.patch

@@ -20,9 +20,9 @@
 +        this.options = options;
      }
  
-+    private <T> T getOverride(String name, T value) {
++    private String getOverride(String name, String value) {
 +        if ((this.options != null) && (this.options.has(name))) {
-+            return (T) this.options.valueOf(name);
++            return String.valueOf(this.options.valueOf(name));
 +        }
 +
 +        return value;