Avoid duplication of parameters when POSTing form URL encoded bodies

Previously if a request body contained form URL encoded content,
parameters would be duplicated in the request body and in the
request URL in the curl, HTTPie, and HTTP request snippets.

This commit updates the affected snippets so that parameters are not
added to the URL when they will also be represented in the request
body.

Closes gh-514

spring-restdocs-core/src/test/java/org/springframework/restdocs/cli/CurlRequestSnippetTests.java

@@ -213,6 +213,20 @@ public class CurlRequestSnippetTests extends AbstractSnippetTests {
 						.method("POST").param("a", "alpha").param("b", "bravo").build());
 	}
 
+	@Test
+	public void postRequestWithOverlappingParametersAndFormUrlEncodedBody()
+			throws IOException {
+		this.snippets.expectCurlRequest().withContents(
+				codeBlock("bash").content("$ curl 'http://localhost/foo' -i -X POST "
+						+ "-H 'Content-Type: application/x-www-form-urlencoded' "
+						+ "-d 'a=alpha&b=bravo'"));
+		new CurlRequestSnippet(this.commandFormatter).document(this.operationBuilder
+				.request("http://localhost/foo").method("POST").content("a=alpha&b=bravo")
+				.header(HttpHeaders.CONTENT_TYPE,
+						MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+				.param("a", "alpha").param("b", "bravo").build());
+	}
+
 	@Test
 	public void putRequestWithOneParameter() throws IOException {
 		this.snippets.expectCurlRequest().withContents(codeBlock("bash")

spring-restdocs-core/src/test/java/org/springframework/restdocs/cli/HttpieRequestSnippetTests.java

@@ -214,6 +214,20 @@ public class HttpieRequestSnippetTests extends AbstractSnippetTests {
 						.method("POST").param("a", "alpha").param("b", "bravo").build());
 	}
 
+	@Test
+	public void postRequestWithOverlappingParametersAndFormUrlEncodedBody()
+			throws IOException {
+		this.snippets.expectHttpieRequest()
+				.withContents(codeBlock("bash").content(
+						"$ echo 'a=alpha&b=bravo' | http POST 'http://localhost/foo' "
+								+ "'Content-Type:application/x-www-form-urlencoded'"));
+		new HttpieRequestSnippet(this.commandFormatter).document(this.operationBuilder
+				.request("http://localhost/foo").method("POST").content("a=alpha&b=bravo")
+				.header(HttpHeaders.CONTENT_TYPE,
+						MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+				.param("a", "alpha").param("b", "bravo").build());
+	}
+
 	@Test
 	public void putRequestWithOneParameter() throws IOException {
 		this.snippets.expectHttpieRequest().withContents(codeBlock("bash")

spring-restdocs-core/src/test/java/org/springframework/restdocs/http/HttpRequestSnippetTests.java

@@ -202,6 +202,23 @@ public class HttpRequestSnippetTests extends AbstractSnippetTests {
 				.param("a", "alpha").param("b", "bravo").content(content).build());
 	}
 
+	@Test
+	public void postRequestWithOverlappingParametersAndFormUrlEncodedBody()
+			throws IOException {
+		String content = "a=alpha&b=bravo";
+		this.snippets.expectHttpRequest()
+				.withContents(httpRequest(RequestMethod.POST, "/foo")
+						.header(HttpHeaders.CONTENT_TYPE,
+								MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+						.header(HttpHeaders.HOST, "localhost").content(content)
+						.header(HttpHeaders.CONTENT_LENGTH, content.getBytes().length));
+		new HttpRequestSnippet().document(this.operationBuilder
+				.request("http://localhost/foo").method("POST").content("a=alpha&b=bravo")
+				.header(HttpHeaders.CONTENT_TYPE,
+						MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+				.param("a", "alpha").param("b", "bravo").build());
+	}
+
 	@Test
 	public void postRequestWithCharset() throws IOException {
 		String japaneseContent = "\u30b3\u30f3\u30c6\u30f3\u30c4";