GH-3123: Don't logout FtpSession if not connected

Fixes #3123

Author: div

spring-integration-ftp/src/main/java/org/springframework/integration/ftp/session/FtpSession.java

@@ -38,6 +38,7 @@
  * @author Oleg Zhurakousky
  * @author Gary Russell
  * @author Artem Bilan
+ * @author Den Ivanov
  *
  * @since 2.0
  */
@@ -154,7 +155,9 @@ public void close() {
 			if (this.readingRaw.get() && !finalizeRaw() && LOGGER.isWarnEnabled()) {
 				LOGGER.warn("Finalize on readRaw() returned false for " + this);
 			}
-			this.client.logout();
+			if (this.client.isConnected()) {
+				this.client.logout();
+			}
 			this.client.disconnect();
 		}
 		catch (Exception e) {

spring-integration-ftp/src/test/java/org/springframework/integration/ftp/session/SessionFactoryTests.java

@@ -69,6 +69,7 @@ protected FTPClient createClientInstance() {
 		sessionFactory.setDataTimeout(789);
 		doReturn(200).when(client).getReplyCode();
 		doReturn(true).when(client).login("foo", null);
+		doReturn(true).when(client).isConnected();
 		FtpSession session = sessionFactory.getSession();
 		verify(client).setConnectTimeout(123);
 		verify(client).setDefaultTimeout(456);
@@ -210,7 +211,6 @@ void testConnectionLimit() throws Exception {
 					session.close();
 				}
 				catch (Exception e) {
-					e.printStackTrace();
 					failures.incrementAndGet();
 				}
 			});