SpringBoot IllegalArgumentException in configuration properties binding

After update from Boot 3.5.0 to 3.5.1, the following arrangement now throws on startup:

@ConfigurationProperties(prefix = "saml")
public @Data class SamlProperties {
    private List<Metadata> additionalMetadata = new ArrayList<>();
    static @Data class Metadata {
        private Set<String> domains = new HashSet<>();
    }
}

saml.additional-metadata:
  - domains: [example3.com]

org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under 'saml.additional-metadata[0].domains' to java.util.Set<java.lang.String>
    at org.springframework.boot.context.properties.bind.Binder.handleBindError(Binder.java:399)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:361)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindDataObject$5(Binder.java:485)
    at org.springframework.boot.context.properties.bind.JavaBeanBinder.bind(JavaBeanBinder.java:124)
    at org.springframework.boot.context.properties.bind.JavaBeanBinder.bind(JavaBeanBinder.java:112)
    at org.springframework.boot.context.properties.bind.JavaBeanBinder.bind(JavaBeanBinder.java:68)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindDataObject$6(Binder.java:488)
    at org.springframework.boot.context.properties.bind.Binder.fromDataObjectBinders(Binder.java:493)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindDataObject$7(Binder.java:487)
    at org.springframework.boot.context.properties.bind.Binder$Context.withIncreasedDepth(Binder.java:606)
    at org.springframework.boot.context.properties.bind.Binder$Context.withDataObject(Binder.java:592)
    at org.springframework.boot.context.properties.bind.Binder.bindDataObject(Binder.java:487)
    at org.springframework.boot.context.properties.bind.Binder.bindObject(Binder.java:426)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:357)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindAggregate$2(Binder.java:447)
    at org.springframework.boot.context.properties.bind.Binder$Context.withSource(Binder.java:582)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindAggregate$3(Binder.java:448)
    at org.springframework.boot.context.properties.bind.IndexedElementsBinder.bindIndexed(IndexedElementsBinder.java:115)
    at org.springframework.boot.context.properties.bind.IndexedElementsBinder.bindIndexed(IndexedElementsBinder.java:91)
    at org.springframework.boot.context.properties.bind.IndexedElementsBinder.bindIndexed(IndexedElementsBinder.java:75)
    at org.springframework.boot.context.properties.bind.CollectionBinder.bindAggregate(CollectionBinder.java:48)
    at org.springframework.boot.context.properties.bind.AggregateBinder.bind(AggregateBinder.java:56)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindAggregate$4(Binder.java:450)
    at org.springframework.boot.context.properties.bind.Binder$Context.withIncreasedDepth(Binder.java:606)
    at org.springframework.boot.context.properties.bind.Binder.bindAggregate(Binder.java:450)
    at org.springframework.boot.context.properties.bind.Binder.bindObject(Binder.java:411)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:357)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindDataObject$5(Binder.java:485)
    at org.springframework.boot.context.properties.bind.JavaBeanBinder.bind(JavaBeanBinder.java:124)
    at org.springframework.boot.context.properties.bind.JavaBeanBinder.bind(JavaBeanBinder.java:112)
    at org.springframework.boot.context.properties.bind.JavaBeanBinder.bind(JavaBeanBinder.java:68)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindDataObject$6(Binder.java:488)
    at org.springframework.boot.context.properties.bind.Binder.fromDataObjectBinders(Binder.java:493)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindDataObject$7(Binder.java:487)
    at org.springframework.boot.context.properties.bind.Binder$Context.withIncreasedDepth(Binder.java:606)
    at org.springframework.boot.context.properties.bind.Binder$Context.withDataObject(Binder.java:592)
    at org.springframework.boot.context.properties.bind.Binder.bindDataObject(Binder.java:487)
    at org.springframework.boot.context.properties.bind.Binder.bindObject(Binder.java:426)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:357)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:345)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:275)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:262)
    at org.springframework.boot.context.properties.ConfigurationPropertiesBinder.bind(ConfigurationPropertiesBinder.java:94)
    at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.bind(ConfigurationPropertiesBindingPostProcessor.java:96)
    ... 206 more
Caused by: java.lang.IllegalArgumentException: 'name' must not be null
    at org.springframework.util.Assert.notNull(Assert.java:181)
    at org.springframework.boot.context.properties.source.ConfigurationPropertyName.isAncestorOf(ConfigurationPropertyName.java:296)
    at org.springframework.boot.context.properties.source.FilteredIterableConfigurationPropertiesSource.<init>(FilteredIterableConfigurationPropertiesSource.java:44)
    at org.springframework.boot.context.properties.source.IterableConfigurationPropertySource.filter(IterableConfigurationPropertySource.java:69)
    at org.springframework.boot.context.properties.bind.IndexedElementsBinder.bindIndexed(IndexedElementsBinder.java:110)
    at org.springframework.boot.context.properties.bind.IndexedElementsBinder.bindIndexed(IndexedElementsBinder.java:91)
    at org.springframework.boot.context.properties.bind.IndexedElementsBinder.bindIndexed(IndexedElementsBinder.java:75)
    at org.springframework.boot.context.properties.bind.CollectionBinder.bindAggregate(CollectionBinder.java:48)
    at org.springframework.boot.context.properties.bind.AggregateBinder.bind(AggregateBinder.java:56)
    at org.springframework.boot.context.properties.bind.Binder.lambda$bindAggregate$4(Binder.java:450)
    at org.springframework.boot.context.properties.bind.Binder$Context.withIncreasedDepth(Binder.java:606)
    at org.springframework.boot.context.properties.bind.Binder.bindAggregate(Binder.java:450)
    at org.springframework.boot.context.properties.bind.Binder.bindObject(Binder.java:411)
    at org.springframework.boot.context.properties.bind.Binder.bind(Binder.java:357)
    ... 248 more

The same error occurs with other similarly nested structures.

Comment From: philwebb

Sorry about that. Duplicates #46032 and we're going to cut a new release immediately.