Backwards incompatibility Many2Many field names affecting (existing) elasticsearch indexes

Overview of the issue

I'm currently in the process of updating a larger application (mostly JHipster generated) to 9.1.0 (from 8.11.0). During this, I noticed a backwards incompatibility, which I worked around by overriding the corresponding changes within my local blueprint. Especially, I'm having an issue with the changes made for #32373 in commit bba9b84eb6dd33d65de52ec6e2928144ea908328

Especially this line here that now force overwrites the plurals here: https://github.com/jhipster/generator-jhipster/blob/1aae62adbbe653a6d2d8eccef85adf132f82551d/generators/base-application/entity.ts#L218-L219

This makes the corresponding many2many relationship fields within the entity class have extra 'es' / 's' by using this logic https://github.com/jhipster/generator-jhipster/blob/1aae62adbbe653a6d2d8eccef85adf132f82551d/lib/utils/string-utils.ts#L39-L45

and effects then here in the class: https://github.com/jhipster/generator-jhipster/blob/1aae62adbbe653a6d2d8eccef85adf132f82551d/generators/java/generators/domain/templates/src/main/java/_package_/_entityPackage_/domain/_persistClass_.java.jhi.ejs#L176

As this class is also used for Elasticsearch indexing, a change in the naming of fields will invalidate existing elasticsearch indexes making data stored as part of those fields be not usable anymore, thus effectively requiring a reindexing: https://github.com/jhipster/generator-jhipster/blob/1aae62adbbe653a6d2d8eccef85adf132f82551d/generators/spring-boot/generators/data-elasticsearch/templates/src/main/java/_package_/_entityPackage_/repository/search/_entityClass_SearchRepository.java.ejs#L112

Motivation for or Use Case

I know, it was part of a major release with 9.0.0, but forcing existing users to perform a reindexing on a possibly multi-million rows relational database (which is my exact use case ;-)) is something that I would like to avoid, if somehow possible.

Also in my case the naming already contained plurals, which now makes the field names sound "funny": from a relationship named "jobs" it produces now "jobses". I also can't just rename the relationships as this again has effect on the column names on database side.

Reproduce the error

Related issues

Suggest a Fix

Just for everyone facing a similar issue, I leave this here, already on how to possibly work around this issue. I have this as part of a local blueprint (extending the spring-boot generator):

get [BaseApplicationGenerator.DEFAULT]() {
    return this.asDefaultTaskGroup({
      async overridePluralNames({ entities }) {
        // 1. Fix entity-level plural properties.
        //    entityInstancePlural → setter parameter names (template: `<%- relationship.otherEntity.entityInstancePlural %>`)
        //    entityClassPlural   → log messages and REST method names (template: `<%- entityClassPlural %>`)
        //    Both are cached as plain values; entityClassPlural = upperFirst(entityNamePlural).
        for (const entity of entities) {
          entity.entityInstancePlural = pluralize(entity.entityInstance);
          entity.entityClassPlural = upperFirst(entity.entityInstancePlural);
        }

        // 2. Fix relationship-level plural properties cached on each relationship object.
        for (const entity of entities) {
          for (const relationship of entity.relationships) {
            const plural = pluralize(relationship.relationshipFieldName);
            relationship.relationshipFieldNamePlural = plural;

            // For collection relationships (oneToMany / manyToMany) the propertyName and
            // all capitalised / snake-cased derivatives must also be recomputed, because
            // they were cached as plain values when the core generator ran and are used
            // by templates for getter/setter names (propertyConsumerName /
            // propertySupplierName are derived from propertyNameCapitalized).
            if (relationship.collection) {
              relationship.propertyName = plural;
              // propertyNameCapitalized / propertyJavaBeanName both equal upperFirst(propertyName)
              // for standard camelCase names; all three are independently cached.
              relationship.propertyNameCapitalized = upperFirst(plural);
              relationship.propertyNameUpperSnakeCase = snakeCase(plural).toUpperCase();
              // propertyJavaBeanName → propertyConsumerName / propertySupplierName are computed
              // in generators/java/application.js and cached as plain values.
              relationship.propertyJavaBeanName = relationship.propertyNameCapitalized;
              relationship.propertyConsumerName = `set${relationship.propertyNameCapitalized}`;
              relationship.propertySupplierName = `get${relationship.propertyNameCapitalized}`;
              // relationshipNameCapitalizedPlural is used for fetchBag method names in
              // RepositoryWithBagRelationshipsImpl; computed in java/bootstrap from
              // pluralize(relationshipNameCapitalized, { force: true }).
              relationship.relationshipNameCapitalizedPlural = relationship.propertyNameCapitalized;
            }
          }
        }
      },
    });
  }

JHipster Version(s)

9.1.0 (worked differently in 8.11.0)

Browsers and Operating System

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