Add header option to multipart helper

Author: Caitlin Bales (MSFT)

src/main/java/com/microsoft/graph/models/extensions/Multipart.java

@@ -7,6 +7,8 @@
 import java.math.BigInteger;
 import java.security.SecureRandom;
 
+import com.microsoft.graph.options.HeaderOption;
+
 /**
  * Helper for submitting multipart data
  * 
@@ -29,12 +31,20 @@ public Multipart() {
 
 	/**
 	 * Get the multipart boundary for use in the request header
-	 * @return The multipart boundary
+	 * @return the multipart boundary
 	 */
 	public String boundary() {
 		return boundary;
 	}
 
+	/**
+	 * Get the Content-Type header to send the multipart request
+	 * @return the multipart header option
+	 */
+	public HeaderOption header() {
+		return new HeaderOption("Content-Type", "multipart/form-data; boundary=\"" + boundary + "\"");
+	}
+	
 	/**
 	 * Add a string part to the multipart body
 	 * @param name The name of the part
@@ -76,7 +86,7 @@ public void addHtmlPart(String name, String content) throws IOException {
 	}
 
 	/**
-	 * Add an image part to the multipart body
+	 * Add an image/jpeg part to the multipart body
 	 * @param name The name of the part
 	 * @param imageFile The image file
 	 * @throws IOException Throws an exception if the output stream cannot be written to

src/test/java/com/microsoft/graph/functional/OneNoteTests.java

@@ -5,6 +5,7 @@
 import com.microsoft.graph.requests.extensions.IOnenotePageCollectionPage;
 import com.microsoft.graph.requests.extensions.IOnenoteSectionCollectionPage;
 import com.microsoft.graph.requests.extensions.ISectionGroupCollectionPage;
+import com.microsoft.graph.serializer.AdditionalDataManager;
 import com.microsoft.graph.requests.extensions.IOnenoteRequestBuilder;
 import com.microsoft.graph.models.extensions.Multipart;
 import com.microsoft.graph.models.extensions.Notebook;
@@ -408,9 +409,7 @@ public void testMultipartPost(){
 
             // Add multipart request header
             List<Option> options = new ArrayList<Option>();
-            options.add(new HeaderOption(
-            		"Content-Type", "multipart/form-data; boundary=\"" + multipart.boundary() + "\""
-            		));
+            options.add(multipart.header());
 
             // Post the multipart content
             OnenotePage page = orb