Reuse IOUtils

src/main/java/org/apache/commons/net/DatagramSocketClient.java

@@ -24,6 +24,8 @@
 import java.time.Duration;
 import java.util.Objects;
 
+import org.apache.commons.io.IOUtils;
+
 /**
  * The DatagramSocketClient provides the basic operations that are required of client objects accessing datagram sockets. It is meant to be subclassed to avoid
  * having to rewrite the same code over and over again to open a socket, close a socket, set timeouts, etc. Of special note is the
@@ -89,9 +91,7 @@ protected DatagramSocket checkOpen() {
      */
     @Override
     public void close() {
-        if (_socket_ != null) {
-            _socket_.close();
-        }
+        IOUtils.closeQuietly(_socket_); // DatagramSocket#close() doesn't throw in its signature.
         _socket_ = null;
         _isOpen_ = false;
     }

src/main/java/org/apache/commons/net/bsd/RExecClient.java

@@ -104,9 +104,7 @@ InputStream createErrorStream() throws IOException {
      */
     @Override
     public void disconnect() throws IOException {
-        if (_errorStream_ != null) {
-            _errorStream_.close();
-        }
+        IOUtils.close(_errorStream_);
         _errorStream_ = null;
         super.disconnect();
     }