A DESCRIPTION OF THE PROBLEM :
In java.net.JarURLConnection.getCertificates() method documentation, the following sentence:
  "Return the Certificate object for this connection if the URL for it points to a JAR file entry, null otherwise."
 should be replaced by:
  "Return*s* the Certificate object*s* for this connection if the URL for it points to a JAR file entry, null otherwise.",
because this method returns an array of certificates and not only one certificate.

[ pluralize "Return" and "object" ]

URL OF FAULTY DOCUMENTATION :
https://docs.oracle.com/javase/8/docs/api/java/net/JarURLConnection.html#getCertificates--