Added Optional<> support (#127).

src/main/java/org/gitlab4j/api/CommitsApi.java

@@ -4,6 +4,7 @@ import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;
 import java.util.Date;
 import java.util.List;
+import java.util.Optional;
 
 import javax.ws.rs.core.Form;
 import javax.ws.rs.core.GenericType;
@@ -194,6 +195,23 @@ public class CommitsApi extends AbstractApi {
         return (response.readEntity(Commit.class));
     }
 
+    /**
+     * Get a specific commit identified by the commit hash or name of a branch or tag as an Optional instance
+     *
+     * GET /projects/:id/repository/commits/:sha
+     *
+     * @param projectId the project ID that the commit belongs to
+     * @param sha a commit hash or name of a branch or tag
+     * @return the Commit for the specified project ID/sha pair as an Optional instance
+     */
+    public Optional<Commit> getOptionalCommit(int projectId, String sha) {
+        try {
+            return (Optional.ofNullable(getCommit(projectId, sha)));
+        } catch (GitLabApiException glae) {
+            return (GitLabApi.createOptionalFromException(glae));
+        }
+    }
+
     /**
      * Get the list of diffs of a commit in a project.
      *

src/main/java/org/gitlab4j/api/DeployKeysApi.java

 package org.gitlab4j.api;
 
 import java.util.List;
+import java.util.Optional;
 
 import javax.ws.rs.core.Form;
 import javax.ws.rs.core.GenericType;
@@ -138,6 +139,23 @@ public class DeployKeysApi extends AbstractApi {
         return (response.readEntity(DeployKey.class));
     }
 
+    /**
+     * Get a single deploy key for the specified project as an Optional instance.
+     *
+     * GET /projects/:id/deploy_keys/:key_id
+     *
+     * @param projectId the ID of the project
+     * @param keyId the ID of the deploy key to delete
+     * @return the DeployKey for the specified project ID and key ID as an Optional instance
+     */
+    public Optional<DeployKey> getOptionalDeployKey(Integer projectId, Integer keyId) {
+        try {
+            return (Optional.ofNullable(getDeployKey(projectId, keyId)));
+        } catch (GitLabApiException glae) {
+            return (GitLabApi.createOptionalFromException(glae));
+        }
+    }
+
     /**
      * Creates a new deploy key for a project.
      *