INT-4443: Use SimpleEC for uriVariablesExpression

JIRA: https://jira.spring.io/browse/INT-4443

**cherry-pick to 5.0.x, 4.3.x**

Polishing; use data binding accessor in test evaluation contexts.

Add `.withInstanceMethods()`

See https://jira.spring.io/browse/SPR-16588?focusedCommentId=158041&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-158041

* Polishing according PR comments

spring-integration-http/src/test/java/org/springframework/integration/http/outbound/HttpOutboundWithinChainTests-context.xml

@@ -8,8 +8,9 @@
 		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">
 
-	<si:chain input-channel="httpOutboundChannelAdapterWithinChain">
-		<outbound-channel-adapter url="http://localhost/test1/%2f" encode-uri="false" rest-template="restTemplate"/>
+	<si:chain id="chain" input-channel="httpOutboundChannelAdapterWithinChain">
+		<outbound-channel-adapter id="adapter" url="http://localhost/test1/%2f" encode-uri="false" rest-template="restTemplate"
+			trusted-spel="true" />
 	</si:chain>
 
 	<beans:bean id="restTemplate" class="org.mockito.Mockito" factory-method="spy">
@@ -22,6 +23,7 @@
 		<outbound-gateway url="http://localhost:51235/%2f/testApps?param={param}"
 						  rest-template="restTemplate"
 						  encode-uri="false"
+						  trusted-spel="true"
 						  expected-response-type-expression="T (org.springframework.integration.http.outbound.HttpRequestExecutingMessageHandlerTests).testParameterizedTypeReference()">
 			<uri-variable name="param" expression="T(java.net.URLEncoder).encode('http Outbound Gateway Within Chain', 'UTF-8')"/>
 						  </outbound-gateway>

spring-integration-http/src/test/java/org/springframework/integration/http/outbound/HttpRequestExecutingMessageHandlerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,9 +16,11 @@
 
 package org.springframework.integration.http.outbound;
 
+import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.mockito.ArgumentMatchers.any;
@@ -706,6 +708,9 @@ public class HttpRequestExecutingMessageHandlerTests {
 		channel.send(MessageBuilder.withPayload("test").build());
 		Mockito.verify(restTemplate).exchange(Mockito.eq(new URI("http://localhost/test1/%2f")),
 				Mockito.eq(HttpMethod.POST), Mockito.any(HttpEntity.class), Mockito.<Class<Object>>eq(null));
+		HttpRequestExecutingMessageHandler handler = ctx.getBean("chain$child.adapter.handler",
+				HttpRequestExecutingMessageHandler.class);
+		assertThat(TestUtils.getPropertyValue(handler, "trustedSpel"), equalTo(Boolean.TRUE));
 		ctx.close();
 	}
 

spring-integration-http/src/test/java/org/springframework/integration/http/outbound/UriVariableExpressionTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -16,7 +16,9 @@
 
 package org.springframework.integration.http.outbound;
 
+import static org.hamcrest.Matchers.containsString;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThat;
 import static org.junit.Assert.fail;
 import static org.mockito.Mockito.mock;
 
@@ -132,13 +134,15 @@ public class UriVariableExpressionTests {
 		handler.setUriVariablesExpression(new SpelExpressionParser().parseExpression("headers.uriVariables"));
 		handler.afterPropertiesSet();
 
-		Map<String, String> expressions = new HashMap<String, String>();
+		Map<String, Object> expressions = new HashMap<String, Object>();
 		expressions.put("foo", "bar");
 
 		Map<String, ?> expressionsMap = ExpressionEvalMap.from(expressions).usingSimpleCallback().build();
 
 		try {
-			handler.handleMessage(MessageBuilder.withPayload("test").setHeader("uriVariables", expressionsMap).build());
+			handler.handleMessage(MessageBuilder.withPayload("test")
+					.setHeader("uriVariables", expressionsMap)
+					.build());
 			fail("Exception expected.");
 		}
 		catch (Exception e) {
@@ -146,6 +150,42 @@ public class UriVariableExpressionTests {
 		}
 
 		assertEquals("http://test/bar", uriHolder.get().toString());
+
+		expressions.put("foo", new SpelExpressionParser().parseExpression("'bar'.toUpperCase()"));
+		try {
+			handler.handleMessage(MessageBuilder.withPayload("test")
+					.setHeader("uriVariables", expressions)
+					.build());
+			fail("Exception expected.");
+		}
+		catch (Exception e) {
+			assertEquals("intentional", e.getCause().getMessage());
+		}
+
+		assertEquals("http://test/BAR", uriHolder.get().toString());
+
+		expressions.put("foo", new SpelExpressionParser().parseExpression("T(Integer).valueOf('42')"));
+		try {
+			handler.handleMessage(MessageBuilder.withPayload("test")
+					.setHeader("uriVariables", expressions)
+					.build());
+			fail("Exception expected.");
+		}
+		catch (Exception e) {
+			assertThat(e.getCause().getMessage(), containsString("Type cannot be found"));
+		}
+
+		handler.setTrustedSpel(true);
+		try {
+			handler.handleMessage(MessageBuilder.withPayload("test")
+					.setHeader("uriVariables", expressions)
+					.build());
+			fail("Exception expected.");
+		}
+		catch (Exception e) {
+			assertEquals("intentional", e.getCause().getMessage());
+		}
+		assertEquals("http://test/42", uriHolder.get().toString());
 	}
 
 }