INT-2867: Add Script Support to inbound-c-a

* Add `<script>` and `<expression>` to `<int:inbound-channel-adapter>`
* Refactoring for `DefaultInboundChannelAdapterParser`
* Introduce `ScriptExecutingMessageSource` to allow scripts' `MessageProcessor`
implementations work as a source for polling endpoint

JIRA: https://jira.springsource.org/browse/INT-2867

INT-2867: documentation

In addition the tests for Lifecycle attributes

Polishing

spring-integration-scripting/src/main/java/org/springframework/integration/scripting/ScriptExecutingMessageSource.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2013 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
+ *
+ *      http://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.scripting;
+
+import org.springframework.integration.endpoint.AbstractMessageSource;
+
+/**
+ * The {@link org.springframework.integration.core.MessageSource} strategy implementation
+ * to produce a {@link org.springframework.integration.Message} from underlying
+ * {@linkplain #scriptMessageProcessor} for polling endpoints.
+ *
+ * @author Artem Bilan
+ * @since 3.0
+ */
+class ScriptExecutingMessageSource extends AbstractMessageSource<Object> {
+
+	private final AbstractScriptExecutingMessageProcessor<?> scriptMessageProcessor;
+
+	public ScriptExecutingMessageSource(AbstractScriptExecutingMessageProcessor<?> scriptMessageProcessor) {
+		this.scriptMessageProcessor = scriptMessageProcessor;
+	}
+
+	@Override
+	protected Object doReceive() {
+		return scriptMessageProcessor.processMessage(null);
+	}
+}

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/config/jsr223/Jsr223InboundChannelAdapterTests-context.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/integration"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:beans="http://www.springframework.org/schema/beans"
+	xmlns:script="http://www.springframework.org/schema/integration/scripting"
+	xsi:schemaLocation="http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
+		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
+		http://www.springframework.org/schema/integration/scripting http://www.springframework.org/schema/integration/scripting/spring-integration-scripting.xsd">
+
+	<channel id="inbound-channel-adapter-channel">
+		<queue/>
+	</channel>
+
+	<inbound-channel-adapter channel="inbound-channel-adapter-channel">
+		<poller max-messages-per-poll="1" fixed-delay="100"/>
+		<script:script lang="ruby">
+			<![CDATA[
+			require "java"
+			include_class 'java.util.Date'
+
+			Date.new
+			]]>
+		</script:script>
+		<header name="foo" value="bar"/>
+	</inbound-channel-adapter>
+
+</beans:beans>

spring-integration-scripting/src/test/java/org/springframework/integration/scripting/config/jsr223/Jsr223InboundChannelAdapterTests.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2013 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
+ *
+ *      http://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.scripting.config.jsr223;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Date;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.hamcrest.Matchers;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.integration.Message;
+import org.springframework.integration.core.PollableChannel;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+/**
+ * @author Artem Bilan
+ * @since 2.0
+ */
+@ContextConfiguration
+@RunWith(SpringJUnit4ClassRunner.class)
+public class Jsr223InboundChannelAdapterTests {
+
+	@Autowired
+	@Qualifier("inbound-channel-adapter-channel")
+	private PollableChannel inboundChannelAdapterChannel;
+
+	@Test
+	public void testInt2867InboundChannelAdapter() throws Exception {
+		Message<?> message = this.inboundChannelAdapterChannel.receive(2000);
+		assertNotNull(message);
+		Object payload = message.getPayload();
+		assertThat(payload, Matchers.instanceOf(Date.class));
+		assertTrue(((Date) payload).before(new Date()));
+		assertEquals("bar", message.getHeaders().get("foo"));
+
+		message = this.inboundChannelAdapterChannel.receive(1000);
+		assertNotNull(message);
+
+		message = this.inboundChannelAdapterChannel.receive(10);
+		assertNull(message);
+	}
+
+}