Adds support for binary payloads (#818)

with this change we're adding support for binary payloads both for HTTP and messaging.

fixes #664

spring-cloud-contract-spec/src/main/groovy/org/springframework/cloud/contract/spec/internal/Body.groovy

@@ -49,6 +49,10 @@ class Body extends DslProperty {
 		this("${bodyAsValue}")
 	}
 
+	Body(byte[] bodyAsValue) {
+		super(bodyAsValue)
+	}
+
 	Body(Number bodyAsValue) {
 		super(bodyAsValue)
 	}
@@ -65,6 +69,10 @@ class Body extends DslProperty {
 		super(bodyAsValue.clientValue, bodyAsValue.serverValue)
 	}
 
+	Body(Serializable serializable) {
+		super(serializable, serializable)
+	}
+
 	Body(MatchingStrategy matchingStrategy) {
 		super(matchingStrategy, matchingStrategy)
 	}

spring-cloud-contract-spec/src/main/groovy/org/springframework/cloud/contract/spec/internal/Common.groovy

@@ -16,10 +16,12 @@
 
 package org.springframework.cloud.contract.spec.internal
 
-import groovy.transform.PackageScope
+import java.nio.charset.Charset
+
 import groovy.transform.TypeChecked
 
 import java.util.regex.Pattern
+
 /**
  * Contains useful common methods for the DSL.
  *
@@ -29,7 +31,6 @@ import java.util.regex.Pattern
  * @since 1.0.0
  */
 @TypeChecked
-@PackageScope
 class Common {
 
 	@Delegate private final RegexPatterns regexPatterns = new RegexPatterns()
@@ -170,12 +171,49 @@ class Common {
 		return new ServerDslProperty(serverValue)
 	}
 
-	String file(String relativePath) {
+	/**
+	 * Read file contents as String
+	 *
+	 * @param relativePath of the file to read
+	 * @return String file contents
+	 */
+	FromFileProperty file(String relativePath) {
+		return file(relativePath, Charset.defaultCharset())
+	}
+
+	/**
+	 * Read file contents as bytes[]
+	 *
+	 * @param relativePath of the file to read
+	 * @return String file contents
+	 */
+	FromFileProperty fileAsBytes(String relativePath) {
+		return new FromFileProperty(fileLocation(relativePath), byte[])
+	}
+
+	/**
+	 * Read file contents as String with the given Charset
+	 *
+	 * @param relativePath of the file to read
+	 * @param charset to use for converting the bytes to String
+	 * @return String file contents
+	 */
+	FromFileProperty file(String relativePath, Charset charset) {
+		return new FromFileProperty(fileLocation(relativePath), String, charset)
+	}
+
+	/**
+	 * Read file contents as array of bytes
+	 *
+	 * @param relativePath of the file to read
+	 * @return file contents as an array of bytes
+	 */
+	private File fileLocation(String relativePath) {
 		URL resource = Thread.currentThread().getContextClassLoader().getResource(relativePath)
 		if (resource == null) {
 			throw new IllegalStateException("File [${relativePath}] is not present")
 		}
-		return new File(resource.toURI()).text
+		return new File(resource.toURI())
 	}
 
 	/**

spring-cloud-contract-spec/src/main/groovy/org/springframework/cloud/contract/spec/internal/DslProperty.groovy

@@ -25,7 +25,7 @@ import groovy.transform.ToString
  */
 @CompileStatic
 @ToString(includePackage = false, includeNames = true)
-class DslProperty<T> {
+class DslProperty<T> implements Serializable {
 
 	final T clientValue
 	final T serverValue

spring-cloud-contract-spec/src/main/groovy/org/springframework/cloud/contract/spec/internal/FromFileProperty.groovy

@@ -0,0 +1,69 @@
+/*
+ *  Copyright 2013-2017 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.cloud.contract.spec.internal
+
+import groovy.transform.CompileStatic
+import groovy.transform.EqualsAndHashCode
+import groovy.transform.ToString
+
+import java.nio.charset.Charset
+
+/**
+ * Represents a property that will become a File content
+ *
+ * @since 2.1.0
+ */
+@CompileStatic
+@EqualsAndHashCode
+@ToString(includePackage = false, includeNames = true)
+class FromFileProperty implements Serializable {
+
+	final File file
+	final Charset charset
+	final Class type
+
+	FromFileProperty(File file, Class type) {
+		this(file, type, Charset.defaultCharset())
+	}
+
+	FromFileProperty(File file, Class type, Charset charset) {
+		this.file = file
+		this.type = type
+		this.charset = charset
+	}
+
+	boolean isString() {
+		return this.type == String
+	}
+
+	boolean isByte() {
+		return this.type == byte[]
+	}
+
+	String asString() {
+		return new String(this.file.bytes, this.charset)
+	}
+
+	String fileName() {
+		return this.file.getName()
+	}
+
+	byte[] asBytes() {
+		return this.file.bytes
+	}
+
+}

spring-cloud-contract-spec/src/main/groovy/org/springframework/cloud/contract/spec/internal/MatchingStrategy.groovy

@@ -55,7 +55,7 @@ class MatchingStrategy extends DslProperty {
 
 	enum Type {
 		EQUAL_TO("equalTo"), CONTAINS("containing"), MATCHING("matching"), NOT_MATCHING("notMatching"),
-		EQUAL_TO_JSON("equalToJson"), EQUAL_TO_XML("equalToXml"), ABSENT("absent")
+		EQUAL_TO_JSON("equalToJson"), EQUAL_TO_XML("equalToXml"), ABSENT("absent"),  BINARY_EQUAL_TO("binaryEqualTo")
 
 		final String name