SeekToCurrentErrorHandler with FixedBackOff ignoring interval - spring kafka 2.7.0 - spring-kafka

Question

I'm using a simple listener factory with SeekToCurrentErrorhandler with FixedBackOff:
#Bean
public ConcurrentKafkaListenerContainerFactory<String, String> stringKafkaListenerContainerFactory(KafkaProperties kafkaProperties) {
ErrorHandlingDeserializer<String> errorHandlingDeserializer = new ErrorHandlingDeserializer<>(new StringDeserializer());
ConsumerFactory<String, String> consumerFactory = new DefaultKafkaConsumerFactory<>(kafkaProperties.buildConsumerProperties(),
errorHandlingDeserializer, errorHandlingDeserializer);
ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory);
factory.getContainerProperties().setAckMode(ContainerProperties.AckMode.RECORD);
factory.setErrorHandler(new SeekToCurrentErrorHandler(new FixedBackOff(10000L, 10L)));
factory.setStatefulRetry(true);
return factory;
}
This configuration is working only partly: it stops (with finally logging ERROR org.springframework.kafka.listener.SeekToCurrentErrorHandler - Backoff FixedBackOff{interval=10000000, currentAttempts=11, maxAttempts=10} exhausted for ...) after the 10 retries - but the interval of 10000ms is ignored: it retries without any delay.
I don't understand why the interval gets ignored...
ConsumerConfig logs following on startup:
2021-05-10 12:19:30,491 [main] INFO org.apache.kafka.clients.consumer.ConsumerConfig - ConsumerConfig values:
allow.auto.create.topics = true
auto.commit.interval.ms = 5000
auto.offset.reset = earliest
bootstrap.servers = [broker:29092]
check.crcs = true
client.dns.lookup = use_all_dns_ips
client.id = some-service-0
client.rack =
connections.max.idle.ms = 540000
default.api.timeout.ms = 60000
enable.auto.commit = false
exclude.internal.topics = true
fetch.max.bytes = 52428800
fetch.max.wait.ms = 500
fetch.min.bytes = 1
group.id = commissioning
group.instance.id = null
heartbeat.interval.ms = 3000
interceptor.classes = []
internal.leave.group.on.close = true
internal.throw.on.fetch.stable.offset.unsupported = false
isolation.level = read_committed
key.deserializer = class org.springframework.kafka.support.serializer.ErrorHandlingDeserializer
max.partition.fetch.bytes = 1048576
max.poll.interval.ms = 300000
max.poll.records = 500
metadata.max.age.ms = 300000
metric.reporters = []
metrics.num.samples = 2
metrics.recording.level = INFO
metrics.sample.window.ms = 30000
partition.assignment.strategy = [class org.apache.kafka.clients.consumer.RangeAssignor]
receive.buffer.bytes = 65536
reconnect.backoff.max.ms = 1000
reconnect.backoff.ms = 50
request.timeout.ms = 30000
retry.backoff.ms = 100
sasl.client.callback.handler.class = null
sasl.jaas.config = null
sasl.kerberos.kinit.cmd = /usr/bin/kinit
sasl.kerberos.min.time.before.relogin = 60000
sasl.kerberos.service.name = null
sasl.kerberos.ticket.renew.jitter = 0.05
sasl.kerberos.ticket.renew.window.factor = 0.8
sasl.login.callback.handler.class = null
sasl.login.class = null
sasl.login.refresh.buffer.seconds = 300
sasl.login.refresh.min.period.seconds = 60
sasl.login.refresh.window.factor = 0.8
sasl.login.refresh.window.jitter = 0.05
sasl.mechanism = GSSAPI
security.protocol = PLAINTEXT
security.providers = null
send.buffer.bytes = 131072
session.timeout.ms = 10000
ssl.cipher.suites = null
ssl.enabled.protocols = [TLSv1.2]
ssl.endpoint.identification.algorithm = https
ssl.engine.factory.class = null
ssl.key.password = null
ssl.keymanager.algorithm = SunX509
ssl.keystore.location = null
ssl.keystore.password = null
ssl.keystore.type = JKS
ssl.protocol = TLSv1.2
ssl.provider = null
ssl.secure.random.implementation = null
ssl.trustmanager.algorithm = PKIX
ssl.truststore.location = null
ssl.truststore.password = null
ssl.truststore.type = JKS
value.deserializer = class org.springframework.kafka.support.serializer.ErrorHandlingDeserializer
any idea why this interval gets ignored?