Fields with underscores work with @DynamoDbBean but not with @DynamoDbImmutable #5589

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1. klach-ocado

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   bugThis issue is a bug.This issue is a bug.

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   on Sep 12, 2024
2. debora-ito

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   on Nov 25, 2024
3. debora-ito

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   dynamodb-enhanced

   on Jan 8, 2025
4. debora-ito commented on Feb 7, 2026

   

   debora-ito

   on Feb 7, 2026

   Last edited by debora-ito

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   @klach-ocado sorry for the lack of updates.

   I can reproduce. My guess is this related to how the Enhanced Client doesn't work well with lombok (#1932), even though it's working with DynamoDbBean.

   I ran a quick test and the double underscore works fine with regular non-lombok immutable classes and TableSchema.fromImmutableClass(), so this is a possible workaround.
5. debora-ito

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   on Feb 7, 2026
6. klach-ocado commented on Feb 10, 2026

   

   klach-ocado

   on Feb 10, 2026

   Last edited by klach-ocado

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   Hi @debora-ito, I'm not sure what you mean that it works with regular non-Lombok immutable classes. The issue is about inconsistent handling of underscores, and without Lombok it looks as follows:

   package com.example;
   
   import org.junit.jupiter.api.Test;
   import software.amazon.awssdk.enhanced.dynamodb.TableSchema;
   import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbBean;
   import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbImmutable;
   import software.amazon.awssdk.enhanced.dynamodb.mapper.annotations.DynamoDbPartitionKey;
   
   import static org.assertj.core.api.Assertions.assertThatCode;
   
   class UnderscoreFieldTest {
   
       @Test
       void shouldResolveTableSchemaFromBean() {
           assertThatCode(() -> TableSchema.fromClass(Bean.class)).doesNotThrowAnyException();
       }
   
       @Test
       void shouldResolveTableSchemaFromImmutable() {
           assertThatCode(() -> TableSchema.fromClass(Immutable.class)).doesNotThrowAnyException();
       }
   
       @DynamoDbBean
       public static class Bean {
   
           private String id;
           private String __encryption_keyId;
   
           @DynamoDbPartitionKey
           public String getId() {
               return this.id;
           }
   
           public String get__encryption_keyId() {
               return this.__encryption_keyId;
           }
   
           public void setId(String id) {
               this.id = id;
           }
   
           public void set__encryption_keyId(String __encryption_keyId) {
               this.__encryption_keyId = __encryption_keyId;
           }
       }
   
       @DynamoDbImmutable(builder = Immutable.ImmutableBuilder.class)
       public static final class Immutable {
   
           private final String id;
           private final String __encryption_keyId;
   
           Immutable(String id, String __encryption_keyId) {
               this.id = id;
               this.__encryption_keyId = __encryption_keyId;
           }
   
           @DynamoDbPartitionKey
           public String getId() {
               return this.id;
           }
   
           public String get__encryption_keyId() {
               return this.__encryption_keyId;
           }
   
           public static class ImmutableBuilder {
               private String id;
               private String __encryption_keyId;
   
               // let's have default public no-arg constructor, to eliminate potential problem caused by Lombok
   
               public ImmutableBuilder id(String id) {
                   this.id = id;
                   return this;
               }
   
               public ImmutableBuilder __encryption_keyId(String __encryption_keyId) {
                   this.__encryption_keyId = __encryption_keyId;
                   return this;
               }
   
               public Immutable build() {
                   return new Immutable(this.id, this.__encryption_keyId);
               }
           }
       }
   }
   

   If get__encryption_keyId getter fits AWS SDK's conventions, then builder's method should fit it too.

   The problem is located here:

   // software.amazon.awssdk.enhanced.dynamodb.internal.immutable.ImmutableIntrospector#normalizeGetterName
       private String normalizeGetterName(Method getter) {
           String getterName = getter.getName();
   
           if (getterName.length() > 2
               && Character.isUpperCase(getterName.charAt(2)) // <--- false for underscore
               && getterName.startsWith(IS_PREFIX)
               && isMethodBoolean(getter)) {
   
               return Character.toLowerCase(getterName.charAt(2)) + getterName.substring(3);
           }
   
           if (getterName.length() > 3
               && Character.isUpperCase(getterName.charAt(3)) // <--- false for underscore
               && getterName.startsWith(GET_PREFIX)) {
   
               return Character.toLowerCase(getterName.charAt(3)) + getterName.substring(4);
           }
   
           return getterName;
       }
   

   ... and later builder's method is not found because normalized getter does not have "get" prefix removed.
7. debora-ito commented on Feb 17, 2026

   

   debora-ito

   on Feb 17, 2026

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   @klach-ocado That is one of the restrictions for the non-lombok immutable classes to work, the getter and the setter must use the same method name - so it works if the getter is public String __encryption_keyId() instead of get__encryption_keyId(). Also, TableSchema.fromImmutableClass() must be used when creating the TableSchema. Other restrictions are documented in our Dev Guide - DynamoDB Enhanced - Work with immutable data classes.
8. debora-ito

   removed their assignment

   on Feb 17, 2026
9. klach-ocado commented on Feb 18, 2026

   

   klach-ocado

   on Feb 18, 2026

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   OK, thank you for clarification, I was not aware of the documented conventions for @DynamoDbImmutable, moreover, I saw AWS examples of @DynamoDbImmutable with Lombok, and I thought getter needs get prefix because it just works for regular names, and because of that other issue with Java records (but accessors' names are not the root cause there).

   Based on that documentation, it works for regular getXyz() getters on a best effort basis. But looking at the source of software.amazon.awssdk.enhanced.dynamodb.internal.immutable.ImmutableIntrospector#normalizeGetterName (quoted above), extending support for cases like get_xyz() or get$xyz() should be simple, it may be enough to replace the Character.isUpperCase(...) conditions with something like isUpperCaseOrNonAlphanumericCharacter(...) checking two things from its name.

   Regarding TableSchema.fromImmutableClass(...), it calls the same code underneath that TableSchema.fromClass(...) calls - the latter autodetects the @DynamoDbImmutable or @DynamoDbBean annotation and calls a proper method depending on that.

   The issue is not a big priority for us, but considering potentially simple fix, it would be nice to fix that with some work in that area. Thanks.