DATAREST-94 - Removed dependency to Guava.

Introduced simple Function interface. Replaced usage of Multimap with Spring's MultiValueMap.

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/util/Function.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2013 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.data.rest.core.util;
+
+/**
+ * Simple function interface.
+ * 
+ * @author Oliver Gierke
+ */
+public interface Function<S, T> {
+
+	T apply(S input);
+}

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/util/MapUtils.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2013 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.data.rest.core.util;
+
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.springframework.util.Assert;
+import org.springframework.util.MultiValueMap;
+
+/**
+ * Helper methods to work with {@link Map}s.
+ * 
+ * @author Oliver Gierke
+ */
+public abstract class MapUtils {
+
+	/**
+	 * Turns a {@link MultiValueMap} into its {@link Map} equivalent.
+	 * 
+	 * @param map must not be {@literal null}.
+	 * @return
+	 */
+	public static <K, V> Map<K, Collection<V>> toMap(MultiValueMap<K, V> map) {
+		
+		Assert.notNull(map, "Given map must not be null!");
+		Map<K, Collection<V>> result = new LinkedHashMap<K, Collection<V>>(map.size());
+
+		for (Entry<K, List<V>> entry : map.entrySet()) {
+			result.put(entry.getKey(), entry.getValue());
+		}
+		
+		return result;
+	}
+}

spring-data-rest-core/src/main/java/org/springframework/data/rest/core/util/UriUtils.java

@@ -4,7 +4,6 @@ import java.net.URI;
 import java.util.List;
 import java.util.Stack;
 
-import com.google.common.base.Function;
 import org.springframework.util.StringUtils;
 import org.springframework.web.util.UriComponentsBuilder;
 

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/util/UriUtilsUnitTests.java

@@ -8,7 +8,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Stack;
 
-import com.google.common.base.Function;
 import org.junit.Test;
 
 /**