[OLINGO-659] Replaced Collection with List

lib/commons-api/src/main/java/org/apache/olingo/commons/api/http/HttpHeader.java

@@ -21,6 +21,7 @@ package org.apache.olingo.commons.api.http;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.List;
 import java.util.Locale;
 
 /**
@@ -183,7 +184,7 @@ public class HttpHeader {
   public static final String ODATA_ENTITY_ID = "OData-EntityID";
 
   private final String name;
-  private final Collection<String> values;
+  private final List<String> values;
 
   /**
    * Create header for given name
@@ -216,8 +217,8 @@ public class HttpHeader {
    * Get all values for this header
    * @return all header values
    */
-  public Collection<String> getValues() {
-    return Collections.unmodifiableCollection(values);
+  public List<String> getValues() {
+    return Collections.unmodifiableList(values);
   }
 
   /**

lib/commons-api/src/main/java/org/apache/olingo/commons/api/http/HttpHeaders.java

@@ -22,6 +22,8 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashMap;
+import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 /**
@@ -104,6 +106,21 @@ public class HttpHeaders {
     return Collections.unmodifiableCollection(headers.values());
   }
 
+
+  /**
+   * Get all headers with the according values.
+   *
+   * @return an unmodifiable Map of header names/values
+   */
+  public Map<String, List<String>> getHeaderToValues() {
+    Map<String, List<String>> result = new HashMap<String, List<String>>();
+    Collection<HttpHeader> allHeaders = headers.values();
+    for (HttpHeader header : allHeaders) {
+      result.put(header.getName(), header.getValues());
+    }
+    return Collections.unmodifiableMap(result);
+  }
+
   /**
    * Get all header names.
    *

lib/server-api/src/main/java/org/apache/olingo/server/api/ODataRequest.java

@@ -20,9 +20,6 @@ package org.apache.olingo.server.api;
 
 import java.io.InputStream;
 import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -124,14 +121,7 @@ public class ODataRequest {
    * @return an unmodifiable Map of header names/values
    */
   public Map<String, List<String>> getAllHeaders() {
-    Collection<HttpHeader> allHeader = headers.getHeaders();
-    Map<String, List<String>> result = new HashMap<String, List<String>>();
-
-    for (HttpHeader httpHeader : allHeader) {
-      result.put(httpHeader.getName(), new ArrayList<String>(httpHeader.getValues()));
-    }
-
-    return Collections.unmodifiableMap(result);
+    return headers.getHeaderToValues();
   }
 
 
@@ -241,7 +231,7 @@ public class ODataRequest {
 
   /**
    * Sets the HTTP protocol used
-   * @param protocol
+   * @param 2protocol
    * @see #getProtocol()
    */
   public void setProtocol(String protocol) {

lib/server-api/src/main/java/org/apache/olingo/server/api/ODataResponse.java

@@ -97,12 +97,7 @@ public class ODataResponse {
    * @return an unmodifiable Map of header names/values
    */
   public Map<String, List<String>> getAllHeaders() {
-    Map<String, List<String>> result = new HashMap<String, List<String>>();
-    Collection<HttpHeader> allHeaders = headers.getHeaders();
-    for (HttpHeader header : allHeaders) {
-      result.put(header.getName(), new ArrayList<String>(header.getValues()));
-    }
-    return Collections.unmodifiableMap(result);
+    return headers.getHeaderToValues();
   }
 
   /**