Fix NPEs in DSL Specs (#8597)

* Fix NPEs in DSL Specs

The `BaseWsInboundGatewaySpec` and `TailAdapterSpec` don't override super methods
and when we call them we fail with NPE since `target` was not populated.

* Fix `BaseWsInboundGatewaySpec` and its inheritors to populate the `target`
from their ctors.
* Remove redundant methods from `BaseWsInboundGatewaySpec` hierarchy
* Propagate `AbstractWebServiceInboundGateway` properties directly to the target
from the `BaseWsInboundGatewaySpec` inheritors
* Override `MessageProducerSpec` methods in the `TailAdapterSpec`
to populate respective option into the `FileTailInboundChannelAdapterFactoryBean`
* Expose more missed options for producer endpoint in the `FileTailInboundChannelAdapterFactoryBean`

**Cherry-pick to `6.0.x` & `5.5.x`**

* * `acceptIfNotNull()` for `errorMessageStrategy` in the `FileTailInboundChannelAdapterFactoryBean`

* * Fix `Unmarshaller` population logic in the `MarshallingWsInboundGatewaySpec`

spring-integration-ws/src/main/java/org/springframework/integration/ws/dsl/BaseWsInboundGatewaySpec.java

@@ -27,6 +27,8 @@ import org.springframework.integration.ws.SoapHeaderMapper;
  * @param <E> the target {@link AbstractWebServiceInboundGateway} implementation type.
  *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 5.3
  *
  */
@@ -35,10 +37,10 @@ public abstract class BaseWsInboundGatewaySpec<
 		extends MessagingGatewaySpec<S, E> {
 
 	/**
-	 * Construct an instance.
+	 * Construct an instance based on the provided {@link AbstractWebServiceInboundGateway}.
 	 */
-	protected BaseWsInboundGatewaySpec() {
-		super(null);
+	protected BaseWsInboundGatewaySpec(E gateway) {
+		super(gateway);
 	}
 
 	/**
@@ -51,15 +53,4 @@ public abstract class BaseWsInboundGatewaySpec<
 		return _this();
 	}
 
-	@Override
-	protected E doGet() {
-		return assemble(create());
-	}
-
-	protected abstract E create();
-
-	protected E assemble(E gateway) {
-		return gateway;
-	}
-
 }

spring-integration-ws/src/main/java/org/springframework/integration/ws/dsl/MarshallingWsInboundGatewaySpec.java

@@ -24,15 +24,18 @@ import org.springframework.oxm.Unmarshaller;
  * The spec for a {@link MarshallingWebServiceInboundGateway}.
  *
  * @author Gary Russell
+ * @author Artem Bilan
+ *
  * @since 5.3
  *
  */
-public class MarshallingWsInboundGatewaySpec extends BaseWsInboundGatewaySpec<MarshallingWsInboundGatewaySpec,
-		MarshallingWebServiceInboundGateway> {
+public class MarshallingWsInboundGatewaySpec
+		extends BaseWsInboundGatewaySpec<MarshallingWsInboundGatewaySpec, MarshallingWebServiceInboundGateway> {
 
-	protected Marshaller gatewayMarshaller; // NOSONAR
 
-	protected Unmarshaller gatewayUnmarshaller; // NOSONAR
+	protected MarshallingWsInboundGatewaySpec() {
+		super(new MarshallingWebServiceInboundGateway());
+	}
 
 	/**
 	 * Specify a marshaller to use.
@@ -40,29 +43,22 @@ public class MarshallingWsInboundGatewaySpec extends BaseWsInboundGatewaySpec<Ma
 	 * @return the spec.
 	 */
 	public MarshallingWsInboundGatewaySpec marshaller(Marshaller marshaller) {
-		this.gatewayMarshaller = marshaller;
+		this.target.setMarshaller(marshaller);
+		if (marshaller instanceof Unmarshaller unmarshaller) {
+			return unmarshaller(unmarshaller);
+		}
 		return this;
 	}
 
 	/**
-	 * Specify an unmarshaller to use. Required if the {@link #gatewayMarshaller} is not also
+	 * Specify an unmarshaller to use. Required if the {@link #marshaller} is not also
 	 * an {@link Unmarshaller}.
 	 * @param unmarshaller the unmarshaller.
 	 * @return the spec.
 	 */
 	public MarshallingWsInboundGatewaySpec unmarshaller(Unmarshaller unmarshaller) {
-		this.gatewayUnmarshaller = unmarshaller;
+		this.target.setUnmarshaller(unmarshaller);
 		return this;
 	}
 
-	@Override
-	protected MarshallingWebServiceInboundGateway create() {
-		if (this.gatewayUnmarshaller != null) {
-			return new MarshallingWebServiceInboundGateway(this.gatewayMarshaller, this.gatewayUnmarshaller);
-		}
-		else {
-			return new MarshallingWebServiceInboundGateway(this.gatewayMarshaller);
-		}
-	}
-
 }

spring-integration-ws/src/main/java/org/springframework/integration/ws/dsl/SimpleWsInboundGatewaySpec.java

@@ -22,30 +22,27 @@ import org.springframework.integration.ws.SimpleWebServiceInboundGateway;
  * The spec for a {@link SimpleWebServiceInboundGateway}.
  *
  * @author Gary Russell
- * @since 5.3
+ * @author Artem Bilan
  *
+ * @since 5.3
  */
-public class SimpleWsInboundGatewaySpec extends BaseWsInboundGatewaySpec<SimpleWsInboundGatewaySpec,
-		SimpleWebServiceInboundGateway> {
+public class SimpleWsInboundGatewaySpec
+		extends BaseWsInboundGatewaySpec<SimpleWsInboundGatewaySpec, SimpleWebServiceInboundGateway> {
 
-	protected boolean extractPayload = true; // NOSONAR
+	protected SimpleWsInboundGatewaySpec() {
+		super(new SimpleWebServiceInboundGateway());
+	}
 
 	/**
 	 * Specify true to extract the payloadSource from the request or use
 	 * the entire request as the payload; default true.
+	 *
 	 * @param extract true to extract.
 	 * @return the spec.
 	 */
 	public SimpleWsInboundGatewaySpec extractPayload(boolean extract) {
-		this.extractPayload = extract;
+		this.target.setExtractPayload(extract);
 		return this;
 	}
 
-	@Override
-	protected SimpleWebServiceInboundGateway create() {
-		SimpleWebServiceInboundGateway gateway = new SimpleWebServiceInboundGateway();
-		gateway.setExtractPayload(this.extractPayload);
-		return gateway;
-	}
-
 }

spring-integration-ws/src/test/java/org/springframework/integration/ws/dsl/WsDslTests.java

@@ -24,6 +24,7 @@ import org.junit.jupiter.api.Test;
 import org.springframework.expression.Expression;
 import org.springframework.expression.common.LiteralExpression;
 import org.springframework.integration.test.util.TestUtils;
+import org.springframework.integration.ws.DefaultSoapHeaderMapper;
 import org.springframework.integration.ws.MarshallingWebServiceInboundGateway;
 import org.springframework.integration.ws.MarshallingWebServiceOutboundGateway;
 import org.springframework.integration.ws.SimpleWebServiceInboundGateway;
@@ -71,10 +72,16 @@ public class WsDslTests {
 
 	@Test
 	void simpleInbound() {
-		SimpleWebServiceInboundGateway gateway = Ws.simpleInboundGateway()
-				.extractPayload(false)
-				.get();
+		DefaultSoapHeaderMapper testHeaderMapper = new DefaultSoapHeaderMapper();
+		SimpleWebServiceInboundGateway gateway =
+				Ws.simpleInboundGateway()
+						.extractPayload(false)
+						.headerMapper(testHeaderMapper)
+						.errorChannel("myErrorChannel")
+						.get();
 		assertThat(TestUtils.getPropertyValue(gateway, "extractPayload", Boolean.class)).isFalse();
+		assertThat(TestUtils.getPropertyValue(gateway, "headerMapper")).isSameAs(testHeaderMapper);
+		assertThat(TestUtils.getPropertyValue(gateway, "errorChannelName")).isEqualTo("myErrorChannel");
 	}
 
 	@Test