code: @Override
      public ListPublicKeysResult listPublicKeys(ListPublicKeysRequest request) {
          request = beforeClientExecution(request);
          return executeListPublicKeys(request);
      }
docs: <p>
  Returns all public keys whose private keys were used to sign the digest files within the specified time range.
  The public key is needed to validate digest files that were signed with its corresponding private key.
  </p>
  <note>
  <p>
  CloudTrail uses different private/public key pairs per region. Each digest file is signed with a private key
  unique to its region. Therefore, when you validate a digest file from a particular region, you must look in the
  same region for its corresponding public key.
  </p>
  </note>
  
  @param listPublicKeysRequest
  Requests the public keys for a specified time range.
  @return Result of the ListPublicKeys operation returned by the service.
  @throws InvalidTimeRangeException
  Occurs if the timestamp values are invalid. Either the start time occurs after the end time or the time
  range is outside the range of possible values.
  @throws UnsupportedOperationException
  This exception is thrown when the requested operation is not supported.
  @throws OperationNotPermittedException
  This exception is thrown when the requested operation is not permitted.
  @throws InvalidTokenException
  Reserved for future use.
  @sample AWSCloudTrail.ListPublicKeys
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/cloudtrail-2013-11-01/ListPublicKeys" target="_top">AWS API
  Documentation</a>