diff --git a/src/main/java/org/eclipsefoundation/git/eca/api/models/GithubCommit.java b/src/main/java/org/eclipsefoundation/git/eca/api/models/GithubCommit.java
index 631c78cf6bb1ce3248afca34b9007921bf88ded2..0165a39c97ba445e036405b276b2bda40437a55a 100644
--- a/src/main/java/org/eclipsefoundation/git/eca/api/models/GithubCommit.java
+++ b/src/main/java/org/eclipsefoundation/git/eca/api/models/GithubCommit.java
@@ -13,6 +13,8 @@ package org.eclipsefoundation.git.eca.api.models;
 
 import java.util.List;
 
+import javax.annotation.Nullable;
+
 import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
 import com.fasterxml.jackson.databind.annotation.JsonPOJOBuilder;
 import com.google.auto.value.AutoValue;
@@ -28,8 +30,9 @@ public abstract class GithubCommit {
 
     public abstract CommitData getCommit();
 
+    @Nullable
     public abstract GithubCommitUser getCommitter();
-
+    @Nullable
     public abstract GithubCommitUser getAuthor();
 
     public abstract List<ParentCommit> getParents();
@@ -45,9 +48,9 @@ public abstract class GithubCommit {
 
         public abstract Builder setCommit(CommitData commit);
 
-        public abstract Builder setCommitter(GithubCommitUser committer);
+        public abstract Builder setCommitter(@Nullable GithubCommitUser committer);
 
-        public abstract Builder setAuthor(GithubCommitUser author);
+        public abstract Builder setAuthor(@Nullable GithubCommitUser author);
 
         public abstract Builder setParents(List<ParentCommit> parents);
 
@@ -57,8 +60,10 @@ public abstract class GithubCommit {
     @AutoValue
     @JsonDeserialize(builder = AutoValue_GithubCommit_CommitData.Builder.class)
     public abstract static class CommitData {
+        @Nullable
         public abstract GitCommitUser getAuthor();
 
+        @Nullable
         public abstract GitCommitUser getCommitter();
 
         public static Builder builder() {
@@ -68,9 +73,9 @@ public abstract class GithubCommit {
         @AutoValue.Builder
         @JsonPOJOBuilder(withPrefix = "set")
         public abstract static class Builder {
-            public abstract Builder setAuthor(GitCommitUser author);
+            public abstract Builder setAuthor(@Nullable GitCommitUser author);
 
-            public abstract Builder setCommitter(GitCommitUser committer);
+            public abstract Builder setCommitter(@Nullable GitCommitUser committer);
 
             public abstract CommitData build();
         }