Tolerate changes to request body reading in Framework 5.1

Previously, MockHttpServletRequest allowed its body to be ready
multiple times using its InputStream. As of recent Spring Framework
5.1 snapshots, this is no longer the case.

This commit moves to directly accessing the request's content as a
byte array using getContentAsByteArray() which was introduced in
Framework 5.0.

Closes gh-515

spring-restdocs-core/build.gradle

@@ -61,4 +61,11 @@ artifacts {
 
 test {
 	jvmArgs "-javaagent:${configurations.jacoco.asPath}=destfile=${buildDir}/jacoco.exec,includes=org.springframework.restdocs.*,excludes=org.springframework.restdocs.mustache.*"
+}
+
+matrixTest {
+	springFramework {
+		group = 'org.springframework'
+		versions = ['5.1.0.BUILD-SNAPSHOT']
+	}
 }

spring-restdocs-mockmvc/build.gradle

@@ -16,4 +16,11 @@ dependencies {
 
 test {
 	jvmArgs "-javaagent:${configurations.jacoco.asPath}=destfile=${buildDir}/jacoco.exec,includes=org.springframework.restdocs.*"
+}
+
+matrixTest {
+	springFramework {
+		group = 'org.springframework'
+		versions = ['5.1.0.BUILD-SNAPSHOT']
+	}
 }

spring-restdocs-mockmvc/src/main/java/org/springframework/restdocs/mockmvc/MockMvcRequestConverter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2017 the original author or authors.
+ * Copyright 2014-2018 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.
@@ -81,8 +81,8 @@ class MockMvcRequestConverter implements RequestConverter<MockHttpServletRequest
 							getRequestUri(mockRequest) + (StringUtils.hasText(queryString)
 									? "?" + queryString : "")),
 					HttpMethod.valueOf(mockRequest.getMethod()),
-					FileCopyUtils.copyToByteArray(mockRequest.getInputStream()), headers,
-					parameters, parts, cookies);
+					mockRequest.getContentAsByteArray(), headers, parameters, parts,
+					cookies);
 		}
 		catch (Exception ex) {
 			throw new ConversionException(ex);

spring-restdocs-webtestclient/build.gradle

@@ -14,4 +14,11 @@ dependencies {
 
 test {
 	jvmArgs "-javaagent:${configurations.jacoco.asPath}=destfile=${buildDir}/jacoco.exec,includes=org.springframework.restdocs.*"
+}
+
+matrixTest {
+	springFramework {
+		group = 'org.springframework'
+		versions = ['5.1.0.BUILD-SNAPSHOT']
+	}
 }