I’m running an AWS Lambda written in Java 21 with Spring Boot 3. My Lambda uses an S3 client, which I instantiate as follows:

@Configuration
public class AwsConfig {
    @Bean
    public S3Client awsS3Client() {
        return S3Client.builder()
                .region(Region.of("us-west-1"))
                .build();
    }
}

Problem:
When I invoke the Lambda multiple times in sequence, the AWS environment appears to create a new S3Client before the previous one is garbage collected. This leads to the following error:

No duplicate IdentityProperty names allowed but both IdentityProperties 7890fbf9 and 25f0f461 have the same namespace (java.lang.String) and name (Bucket). IdentityProperty should be referenced from a shared static constant to protect against erroneous or unexpected collisions.

If I wait 5 to 7 minutes before rerunning the lambda, everything works perfectly fine, but it's obviously not acceptable.

From debugging, I see this comes from the AWS SDK’s IdentityProperty class, specifically:

private static final ConcurrentMap<Pair<String, String>, IdentityProperty<?>> NAME_HISTORY = new ConcurrentHashMap<>();

private void ensureUnique() {
    IdentityProperty<?> prev = NAME_HISTORY.putIfAbsent(Pair.of(namespace, name), this);
    Validate.isTrue(prev == null,
        "No duplicate IdentityProperty names allowed but both IdentityProperties %s and %s have the same "
        + "namespace (%s) and name (%s). IdentityProperty should be referenced from a shared static constant to "
        + "protect against erroneous or unexpected collisions.",
        Integer.toHexString(System.identityHashCode(prev)),
        Integer.toHexString(System.identityHashCode(this)),
        namespace,
        name);
}

It seems that after the first Lambda invocation, NAME_HISTORY is not cleared, so subsequent invocations fail when trying to register the same "java.lang.String"/"Bucket" key.

This method is called by S3ExpressAuthSchemeProvider, which is in turn called by DefaultS3ClientBuilder.

What I’ve tried:

• Declaring the S3Client as a static class variable
• Using @Scope("prototype") for the bean
• (As a hack) Removing the property from the NAME_HISTORY map via reflection (which just led to a similar error for another property)
• Various other bean lifecycle and instantiation strategies

Question:

• How can I prevent this error?