Apply NullAbility to sftp module

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

@@ -511,7 +511,7 @@ protected boolean shouldMarkSessionAsDirty(Exception ex) {
 	}
 
 	@Override
-	public <T, C> T executeWithClient(ClientCallback<C, T> callback) {
+	public <T, C> @Nullable T executeWithClient(ClientCallback<C, T> callback) {
 		throw new UnsupportedOperationException("executeWithClient() is not supported by the generic template");
 	}
 

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

@@ -16,6 +16,8 @@
 
 package org.springframework.integration.file.remote.server;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.integration.events.IntegrationEvent;
 
 /**
@@ -34,7 +36,7 @@ public FileServerEvent(Object source) {
 		super(source);
 	}
 
-	public FileServerEvent(Object source, Throwable cause) {
+	public FileServerEvent(Object source, @Nullable Throwable cause) {
 		super(source, cause);
 	}
 

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/config/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes for configuration - parsers, namespace handlers.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.config;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/dsl/Sftp.java

@@ -20,6 +20,7 @@
 import java.util.Comparator;
 
 import org.apache.sshd.sftp.client.SftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.remote.MessageSessionCallback;
 import org.springframework.integration.file.remote.RemoteFileTemplate;
@@ -28,7 +29,6 @@
 import org.springframework.integration.file.support.FileExistsMode;
 import org.springframework.integration.sftp.gateway.SftpOutboundGateway;
 import org.springframework.integration.sftp.session.SftpRemoteFileTemplate;
-import org.springframework.lang.Nullable;
 
 /**
  * The factory for SFTP components.

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/dsl/SftpInboundChannelAdapterSpec.java

@@ -20,6 +20,7 @@
 import java.util.Comparator;
 
 import org.apache.sshd.sftp.client.SftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.dsl.RemoteFileInboundChannelAdapterSpec;
 import org.springframework.integration.file.filters.CompositeFileListFilter;
@@ -31,7 +32,6 @@
 import org.springframework.integration.sftp.filters.SftpSimplePatternFileListFilter;
 import org.springframework.integration.sftp.inbound.SftpInboundFileSynchronizer;
 import org.springframework.integration.sftp.inbound.SftpInboundFileSynchronizingMessageSource;
-import org.springframework.lang.Nullable;
 
 /**
  * A {@link RemoteFileInboundChannelAdapterSpec} for an {@link SftpInboundFileSynchronizingMessageSource}.

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/dsl/SftpStreamingInboundChannelAdapterSpec.java

@@ -19,6 +19,7 @@
 import java.util.Comparator;
 
 import org.apache.sshd.sftp.client.SftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.dsl.RemoteFileStreamingInboundChannelAdapterSpec;
 import org.springframework.integration.file.filters.CompositeFileListFilter;
@@ -29,7 +30,6 @@
 import org.springframework.integration.sftp.filters.SftpRegexPatternFileListFilter;
 import org.springframework.integration.sftp.filters.SftpSimplePatternFileListFilter;
 import org.springframework.integration.sftp.inbound.SftpStreamingMessageSource;
-import org.springframework.lang.Nullable;
 
 /**
  * @author Gary Russell

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/dsl/package-info.java

@@ -1,6 +1,5 @@
 /**
  * Provides SFTP Components for the Java DSL.
  */
-@org.springframework.lang.NonNullApi
-@org.springframework.lang.NonNullFields
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.dsl;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/filters/SftpRegexPatternFileListFilter.java

@@ -43,7 +43,7 @@ public SftpRegexPatternFileListFilter(Pattern pattern) {
 
 	@Override
 	protected String getFilename(SftpClient.DirEntry entry) {
-		return (entry != null) ? entry.getFilename() : null;
+		return entry.getFilename();
 	}
 
 	@Override

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/filters/SftpSimplePatternFileListFilter.java

@@ -37,7 +37,7 @@ public SftpSimplePatternFileListFilter(String pattern) {
 
 	@Override
 	protected String getFilename(SftpClient.DirEntry entry) {
-		return (entry != null) ? entry.getFilename() : null;
+		return entry.getFilename();
 	}
 
 	@Override

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/filters/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting SFTP file filtering.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.filters;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/gateway/SftpOutboundGateway.java

@@ -23,6 +23,7 @@
 import java.util.stream.Collectors;
 
 import org.apache.sshd.sftp.client.SftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.remote.AbstractFileInfo;
 import org.springframework.integration.file.remote.ClientCallbackWithoutResult;
@@ -33,7 +34,6 @@
 import org.springframework.integration.file.remote.session.SessionFactory;
 import org.springframework.integration.sftp.session.SftpFileInfo;
 import org.springframework.integration.sftp.session.SftpRemoteFileTemplate;
-import org.springframework.lang.Nullable;
 
 /**
  * Outbound Gateway for performing remote file operations via SFTP.

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/gateway/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting SFTP gateways.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.gateway;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/inbound/SftpInboundFileSynchronizer.java

@@ -47,12 +47,12 @@ public SftpInboundFileSynchronizer(SessionFactory<SftpClient.DirEntry> sessionFa
 
 	@Override
 	protected boolean isFile(SftpClient.DirEntry file) {
-		return file != null && file.getAttributes().isRegularFile();
+		return file.getAttributes().isRegularFile();
 	}
 
 	@Override
 	protected String getFilename(SftpClient.DirEntry file) {
-		return file != null ? file.getFilename() : null;
+		return file.getFilename();
 	}
 
 	@Override

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/inbound/SftpInboundFileSynchronizingMessageSource.java

@@ -20,6 +20,7 @@
 import java.util.Comparator;
 
 import org.apache.sshd.sftp.client.SftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizer;
 import org.springframework.integration.file.remote.synchronizer.AbstractInboundFileSynchronizingMessageSource;
@@ -42,7 +43,7 @@ public SftpInboundFileSynchronizingMessageSource(AbstractInboundFileSynchronizer
 	}
 
 	public SftpInboundFileSynchronizingMessageSource(AbstractInboundFileSynchronizer<SftpClient.DirEntry> synchronizer,
-			Comparator<File> comparator) {
+			@Nullable Comparator<File> comparator) {
 
 		super(synchronizer, comparator);
 	}

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/inbound/SftpStreamingMessageSource.java

@@ -22,6 +22,7 @@
 import java.util.List;
 
 import org.apache.sshd.sftp.client.SftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.remote.AbstractFileInfo;
 import org.springframework.integration.file.remote.AbstractRemoteFileStreamingMessageSource;
@@ -58,7 +59,7 @@ public SftpStreamingMessageSource(RemoteFileTemplate<SftpClient.DirEntry> templa
 	 */
 	@SuppressWarnings("this-escape")
 	public SftpStreamingMessageSource(RemoteFileTemplate<SftpClient.DirEntry> template,
-			Comparator<SftpClient.DirEntry> comparator) {
+			@Nullable Comparator<SftpClient.DirEntry> comparator) {
 
 		super(template, comparator);
 		doSetFilter(new SftpPersistentAcceptOnceFileListFilter(new SimpleMetadataStore(), "sftpStreamingMessageSource"));
@@ -80,7 +81,7 @@ protected List<AbstractFileInfo<SftpClient.DirEntry>> asFileInfoList(Collection<
 
 	@Override
 	protected boolean isDirectory(SftpClient.DirEntry file) {
-		return file != null && file.getAttributes().isDirectory();
+		return file.getAttributes().isDirectory();
 	}
 
 }

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/inbound/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting inbound endpoints.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.inbound;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/outbound/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes for the SFTP outbound channel adapter.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.outbound;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/ApacheMinaSftpEvent.java

@@ -17,6 +17,7 @@
 package org.springframework.integration.sftp.server;
 
 import org.apache.sshd.server.session.ServerSession;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.integration.file.remote.server.FileServerEvent;
 
@@ -35,7 +36,7 @@ public ApacheMinaSftpEvent(Object source) {
 		super(source);
 	}
 
-	public ApacheMinaSftpEvent(Object source, Throwable cause) {
+	public ApacheMinaSftpEvent(Object source, @Nullable Throwable cause) {
 		super(source, cause);
 	}
 

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/ApacheMinaSftpEventListener.java

@@ -24,6 +24,7 @@
 import org.apache.sshd.server.session.ServerSession;
 import org.apache.sshd.sftp.server.FileHandle;
 import org.apache.sshd.sftp.server.SftpEventListener;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.BeanNameAware;
 import org.springframework.beans.factory.InitializingBean;
@@ -45,9 +46,10 @@
 public class ApacheMinaSftpEventListener
 		implements SftpEventListener, ApplicationEventPublisherAware, BeanNameAware, InitializingBean {
 
+	@SuppressWarnings("NullAway.Init")
 	private ApplicationEventPublisher applicationEventPublisher;
 
-	private String beanName;
+	private @Nullable String beanName;
 
 	@Override
 	public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
@@ -63,7 +65,7 @@ public void setBeanName(String name) {
 		this.beanName = name;
 	}
 
-	public String getBeanName() {
+	public @Nullable String getBeanName() {
 		return this.beanName;
 	}
 

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/DirectoryCreatedEvent.java

@@ -19,8 +19,6 @@
 import java.nio.file.Path;
 import java.util.Map;
 
-import org.springframework.lang.Nullable;
-
 /**
  * An event emitted when a directory is created.
  *
@@ -43,7 +41,6 @@ public DirectoryCreatedEvent(Object source, Path path, Map<String, ?> attrs) {
 		this.attrs = attrs;
 	}
 
-	@Nullable
 	public Path getPath() {
 		return this.path;
 	}

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/FileWrittenEvent.java

@@ -18,7 +18,7 @@
 
 import java.nio.file.Path;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * An event that is emitted when a file is written.
@@ -48,7 +48,6 @@ public String getRemoteHandle() {
 		return this.remoteHandle;
 	}
 
-	@Nullable
 	public Path getFile() {
 		return this.file;
 	}

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/PathMovedEvent.java

@@ -18,7 +18,7 @@
 
 import java.nio.file.Path;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * An event emitted when a path is moved.
@@ -41,12 +41,10 @@ public PathMovedEvent(Object source, Path srcPath, Path dstPath, @Nullable Throw
 		this.dstPath = dstPath;
 	}
 
-	@Nullable
 	public Path getSrcPath() {
 		return this.srcPath;
 	}
 
-	@Nullable
 	public Path getDstPath() {
 		return this.dstPath;
 	}

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/PathRemovedEvent.java

@@ -18,7 +18,7 @@
 
 import java.nio.file.Path;
 
-import org.springframework.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 
 /**
  * An event emitted when a file or directory is removed.
@@ -41,7 +41,6 @@ public PathRemovedEvent(Object source, Path path, boolean isDirectory, @Nullable
 		this.isDirectory = isDirectory;
 	}
 
-	@Nullable
 	public Path getPath() {
 		return this.path;
 	}

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/server/package-info.java

@@ -1,4 +1,5 @@
 /**
  * Provides classes related to SFTP servers.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.sftp.server;

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/session/DefaultSftpSessionFactory.java

@@ -51,6 +51,7 @@
 import org.apache.sshd.sftp.client.SftpVersionSelector;
 import org.apache.sshd.sftp.client.impl.AbstractSftpClient;
 import org.apache.sshd.sftp.client.impl.DefaultSftpClient;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.core.io.Resource;
@@ -94,35 +95,37 @@ public class DefaultSftpSessionFactory
 
 	private final boolean isSharedSession;
 
-	private final Lock sharedSessionLock;
+	private final @Nullable Lock sharedSessionLock;
 
 	private boolean isInnerClient = false;
 
+	@SuppressWarnings("NullAway.Init")
 	private String host;
 
 	private int port = SshConstants.DEFAULT_PORT;
 
+	@SuppressWarnings("NullAway.Init")
 	private String user;
 
-	private String password;
+	private @Nullable String password;
 
-	private HostConfigEntry hostConfig;
+	private @Nullable HostConfigEntry hostConfig;
 
-	private Resource knownHosts;
+	private @Nullable Resource knownHosts;
 
-	private Resource privateKey;
+	private @Nullable Resource privateKey;
 
-	private String privateKeyPassphrase;
+	private @Nullable String privateKeyPassphrase;
 
-	private UserInteraction userInteraction;
+	private @Nullable UserInteraction userInteraction;
 
 	private boolean allowUnknownKeys = false;
 
 	private Integer timeout = (int) IntegrationContextUtils.DEFAULT_TIMEOUT;
 
 	private SftpVersionSelector sftpVersionSelector = SftpVersionSelector.CURRENT;
 
-	private volatile SftpClient sharedSftpClient;
+	private volatile @Nullable SftpClient sharedSftpClient;
 
 	private Consumer<SshClient> sshClientConfigurer = (sshClient) -> {
 	};