GH-3271: Close session on error in stream source

Fixes https://github.com/spring-projects/spring-integration/issues/3271

When exception happens at `.withPayload(session.readRaw(remotePath))`
in the `AbstractRemoteFileStreamingMessageSource` we don't close session.
The resource leaking happens in the caching session factory

* Add `session.close();` into the `catch (IOException e) {`
in the `AbstractRemoteFileStreamingMessageSource.doReceive()`
to clean up resources properly

**Cherry-pick to 5.2.x, 5.1.x & 4.3.x**

spring-integration-file/src/main/java/org/springframework/integration/file/remote/AbstractRemoteFileStreamingMessageSource.java

@@ -194,6 +194,7 @@ public abstract class AbstractRemoteFileStreamingMessageSource<F>
 									this.fileInfoJson ? file.toJson() : file);
 				}
 				catch (IOException e) {
+					session.close();
 					throw new UncheckedIOException("IOException when retrieving " + remotePath, e);
 				}
 			}

spring-integration-file/src/test/java/org/springframework/integration/file/remote/RemoteFileStreamingMessageSourceTests.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright 2015-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.integration.file.remote;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.integration.file.remote.session.CachingSessionFactory;
+import org.springframework.integration.file.remote.session.Session;
+import org.springframework.integration.file.remote.session.SessionFactory;
+
+/**
+ * @author Lukas Gemela
+ * @author Artem Bilan
+ *
+ * @since 5.2.2
+ *
+ */
+public class RemoteFileStreamingMessageSourceTests {
+
+	@Test
+	@SuppressWarnings("unchecked")
+	public void sessionReturnedToCacheProperlyOnDoReceive() throws IOException {
+		Session<String> session = mock(Session.class);
+		when(session.readRaw(anyString())).thenThrow(IOException.class);
+		when(session.list("remoteDirectory")).thenReturn(new String[] { "file1" });
+
+		SessionFactory<String> sessionFactory = mock(SessionFactory.class);
+		when(sessionFactory.getSession()).thenReturn(session);
+
+		CachingSessionFactory<String> cachingSessionFactory = new CachingSessionFactory<>(sessionFactory, 1);
+		RemoteFileTemplate<String> remoteFileTemplate = new RemoteFileTemplate<>(cachingSessionFactory);
+
+		TestRemoteFileStreamingMessageSource testRemoteFileStreamingMessageSource =
+				new TestRemoteFileStreamingMessageSource(remoteFileTemplate, null);
+
+		testRemoteFileStreamingMessageSource.setRemoteDirectory("remoteDirectory");
+		testRemoteFileStreamingMessageSource.setBeanFactory(mock(BeanFactory.class));
+		testRemoteFileStreamingMessageSource.start();
+
+		assertThatExceptionOfType(UncheckedIOException.class)
+				.isThrownBy(testRemoteFileStreamingMessageSource::doReceive);
+
+		assertThat(cachingSessionFactory.getSession()).isNotNull();
+	}
+
+	static class TestRemoteFileStreamingMessageSource extends AbstractRemoteFileStreamingMessageSource<String> {
+
+		TestRemoteFileStreamingMessageSource(RemoteFileTemplate<String> template, Comparator<String> comparator) {
+			super(template, comparator);
+		}
+
+		@Override
+		protected List<AbstractFileInfo<String>> asFileInfoList(Collection<String> files) {
+			return files
+					.stream()
+					.map(TestFileInfo::new)
+					.collect(Collectors.toList());
+		}
+
+		@Override
+		protected boolean isDirectory(String file) {
+			return false;
+		}
+
+		@Override
+		public String getComponentType() {
+			return null;
+		}
+
+	}
+
+	static class TestFileInfo extends AbstractFileInfo<String> {
+
+		TestFileInfo(String fileName) {
+			this.fileName = fileName;
+		}
+
+		private final String fileName;
+
+		@Override
+		public boolean isDirectory() {
+			return false;
+		}
+
+		@Override
+		public boolean isLink() {
+			return false;
+		}
+
+		@Override
+		public long getSize() {
+			return 0;
+		}
+
+		@Override
+		public long getModified() {
+			return 0;
+		}
+
+		@Override
+		public String getFilename() {
+			return fileName;
+		}
+
+		@Override
+		public String getPermissions() {
+			return null;
+		}
+
+		@Override
+		public String getFileInfo() {
+			return null;
+		}
+
+	}
+
+}