diff --git a/core/src/main/java/google/registry/model/EppResource.java b/core/src/main/java/google/registry/model/EppResource.java
index 753d319d1..fda0c6879 100644
--- a/core/src/main/java/google/registry/model/EppResource.java
+++ b/core/src/main/java/google/registry/model/EppResource.java
@@ -155,9 +155,16 @@ public abstract class EppResource extends BackupGroupRoot implements Buildable {
     return repoId;
   }
 
-  /** This method exists solely to satisfy Hibernate. Use {@link Builder} instead. */
-  @SuppressWarnings("UnusedMethod")
-  private void setRepoId(String repoId) {
+  /**
+   * Sets the repository ID.
+   *
+   * <p>This should only be used for restoring the repo id of an object being loaded in a PostLoad
+   * method (effectively, when it is still under construction by Hibernate). In all other cases, the
+   * object should be regarded as immutable and changes should go through a Builder.
+   *
+   * <p>In addition to this special case use, this method must exist to satisfy Hibernate.
+   */
+  public void setRepoId(String repoId) {
     this.repoId = repoId;
   }
 
diff --git a/core/src/main/java/google/registry/model/contact/ContactHistory.java b/core/src/main/java/google/registry/model/contact/ContactHistory.java
index 033a51329..61bc07119 100644
--- a/core/src/main/java/google/registry/model/contact/ContactHistory.java
+++ b/core/src/main/java/google/registry/model/contact/ContactHistory.java
@@ -115,7 +115,10 @@ public class ContactHistory extends HistoryEntry implements SqlEntity {
       contactBase = null;
     }
     if (contactBase != null && contactBase.getRepoId() == null) {
-      contactBase = contactBase.asBuilder().setRepoId(parent.getName()).build();
+      // contactBase hasn't been fully constructed yet, so it's ok to go in and mutate it.  Though
+      // the use of the Builder is not necessarily problematic in this case, this is still safer as
+      // the Builder can do things like comparisons that compute the hash code.
+      contactBase.setRepoId(parent.getName());
     }
   }
 
diff --git a/core/src/main/java/google/registry/model/domain/DomainHistory.java b/core/src/main/java/google/registry/model/domain/DomainHistory.java
index 0eb6af37f..d96388f10 100644
--- a/core/src/main/java/google/registry/model/domain/DomainHistory.java
+++ b/core/src/main/java/google/registry/model/domain/DomainHistory.java
@@ -258,7 +258,10 @@ public class DomainHistory extends HistoryEntry implements SqlEntity {
         domainContent = null;
       } else {
         if (domainContent.getRepoId() == null) {
-          domainContent = domainContent.asBuilder().setRepoId(parent.getName()).build();
+          // domainContent still hasn't been fully constructed yet, so it's ok to go in and mutate
+          // it.  In fact, we have to because going through the builder causes the hash codes of
+          // contained objects to be calculated prematurely.
+          domainContent.setRepoId(parent.getName());
         }
       }
     }
diff --git a/core/src/main/java/google/registry/model/host/HostHistory.java b/core/src/main/java/google/registry/model/host/HostHistory.java
index 2526073b8..0930f03c2 100644
--- a/core/src/main/java/google/registry/model/host/HostHistory.java
+++ b/core/src/main/java/google/registry/model/host/HostHistory.java
@@ -116,7 +116,10 @@ public class HostHistory extends HistoryEntry implements SqlEntity {
       hostBase = null;
     }
     if (hostBase != null && hostBase.getRepoId() == null) {
-      hostBase = hostBase.asBuilder().setRepoId(parent.getName()).build();
+      // hostBase hasn't been fully constructed yet, so it's ok to go in and mutate it.  Though the
+      // use of the Builder is not necessarily problematic in this case, this is still safer as the
+      // Builder can do things like comparisons that compute the hash code.
+      hostBase.setRepoId(parent.getName());
     }
   }
 
diff --git a/core/src/main/java/google/registry/model/transfer/DomainTransferData.java b/core/src/main/java/google/registry/model/transfer/DomainTransferData.java
index 397746243..6696bddd8 100644
--- a/core/src/main/java/google/registry/model/transfer/DomainTransferData.java
+++ b/core/src/main/java/google/registry/model/transfer/DomainTransferData.java
@@ -164,7 +164,6 @@ public class DomainTransferData extends TransferData<DomainTransferData.Builder>
       serverApproveEntities = null;
       postLoad();
     }
-    hashCode = null; // reset the hash code since we may have changed the entities
   }
 
   /**