Allow request and path parameters to be marked as optional

Closes gh-169

spring-restdocs-core/src/test/java/org/springframework/restdocs/request/PathParametersSnippetTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2015 the original author or authors.
+ * Copyright 2014-2016 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.
@@ -71,6 +71,22 @@ public class PathParametersSnippetTests extends AbstractSnippetTests {
 								"/{a}/{b}").build());
 	}
 
+	@Test
+	public void missingOptionalPathParameter() throws IOException {
+		this.snippet
+				.expectPathParameters(
+						"missing-optional-path-parameter")
+				.withContents(tableWithTitleAndHeader(
+						this.templateFormat == TemplateFormats.asciidoctor() ? "/{a}"
+								: "`/{a}`",
+						"Parameter", "Description").row("a", "one").row("b", "two"));
+		new PathParametersSnippet(Arrays.asList(parameterWithName("a").description("one"),
+				parameterWithName("b").description("two").optional())).document(
+						operationBuilder("missing-optional-path-parameter").attribute(
+								RestDocumentationGenerator.ATTRIBUTE_NAME_URL_TEMPLATE,
+								"/{a}").build());
+	}
+
 	@Test
 	public void pathParametersWithQueryString() throws IOException {
 		this.snippet.expectPathParameters("path-parameters-with-query-string")

spring-restdocs-core/src/test/java/org/springframework/restdocs/request/RequestParametersSnippetTests.java

@@ -80,6 +80,19 @@ public class RequestParametersSnippetTests extends AbstractSnippetTests {
 								.param("b", "bravo").build());
 	}
 
+	@Test
+	public void missingOptionalRequestParameter() throws IOException {
+		this.snippet.expectRequestParameters("missing-optional-request-parameter")
+				.withContents(tableWithHeader("Parameter", "Description").row("a", "one")
+						.row("b", "two"));
+		new RequestParametersSnippet(
+				Arrays.asList(parameterWithName("a").description("one").optional(),
+						parameterWithName("b").description("two"))).document(
+								operationBuilder("missing-optional-request-parameter")
+										.request("http://localhost").param("b", "bravo")
+										.build());
+	}
+
 	@Test
 	public void requestParametersWithCustomAttributes() throws IOException {
 		TemplateResourceResolver resolver = mock(TemplateResourceResolver.class);