Add Comparator to (S)FTP order-sensitive tests

https://build.spring.io/browse/INT-MASTER-583/

**Cherry-pick to 4.3.x**

Author: artembilan

spring-integration-ftp/src/test/java/org/springframework/integration/ftp/inbound/FtpStreamingMessageSourceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 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.
@@ -23,6 +23,7 @@
 import static org.junit.Assert.assertThat;
 
 import java.io.InputStream;
+import java.util.Comparator;
 
 import org.apache.commons.net.ftp.FTPFile;
 import org.junit.Test;
@@ -38,6 +39,7 @@
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.endpoint.SourcePollingChannelAdapter;
 import org.springframework.integration.file.FileHeaders;
+import org.springframework.integration.file.remote.FileInfo;
 import org.springframework.integration.file.remote.session.SessionFactory;
 import org.springframework.integration.ftp.FtpTestSupport;
 import org.springframework.integration.ftp.session.FtpFileInfo;
@@ -124,7 +126,8 @@ public PollerMetadata defaultPoller() {
 		@Bean
 		@InboundChannelAdapter(channel = "stream")
 		public MessageSource<InputStream> ftpMessageSource() {
-			FtpStreamingMessageSource messageSource = new FtpStreamingMessageSource(template(), null);
+			FtpStreamingMessageSource messageSource = new FtpStreamingMessageSource(template(),
+					Comparator.comparing(FileInfo::getFilename));
 			messageSource.setRemoteDirectory("ftpSource/");
 			return messageSource;
 		}

spring-integration-sftp/src/test/java/org/springframework/integration/sftp/dsl/SftpTests.java

@@ -123,7 +123,7 @@ public void testSftpInboundStreamFlow() throws Exception {
 		message = out.receive(10_000);
 		assertNotNull(message);
 		assertThat(message.getPayload(), instanceOf(InputStream.class));
-		assertThat(message.getHeaders().get(FileHeaders.REMOTE_FILE), isOneOf("sftpSource1.txt", "sftpSource2.txt"));
+		assertThat(message.getHeaders().get(FileHeaders.REMOTE_FILE), isOneOf(" sftpSource1.txt", "sftpSource2.txt"));
 		((InputStream) message.getPayload()).close();
 		new IntegrationMessageHeaderAccessor(message).getCloseableResource().close();
 

spring-integration-sftp/src/test/java/org/springframework/integration/sftp/inbound/SftpStreamingMessageSourceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016 the original author or authors.
+ * Copyright 2016-2017 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.
@@ -23,6 +23,7 @@
 import static org.junit.Assert.assertThat;
 
 import java.io.InputStream;
+import java.util.Comparator;
 
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -37,6 +38,7 @@
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.endpoint.SourcePollingChannelAdapter;
 import org.springframework.integration.file.FileHeaders;
+import org.springframework.integration.file.remote.FileInfo;
 import org.springframework.integration.file.remote.session.SessionFactory;
 import org.springframework.integration.scheduling.PollerMetadata;
 import org.springframework.integration.sftp.SftpTestSupport;
@@ -125,7 +127,8 @@ public PollerMetadata defaultPoller() {
 		@Bean
 		@InboundChannelAdapter(channel = "stream")
 		public MessageSource<InputStream> sftpMessageSource() {
-			SftpStreamingMessageSource messageSource = new SftpStreamingMessageSource(template(), null);
+			SftpStreamingMessageSource messageSource = new SftpStreamingMessageSource(template(),
+					Comparator.comparing(FileInfo::getFilename));
 			messageSource.setRemoteDirectory("sftpSource/");
 			return messageSource;
 		}