AWS: client credentials provider NPE

Start in org.apache.iceberg.aws.AwsClientProperties#credentialsProvider and inspect the clientCredentialsProviderProperties handling before PropertyUtil.filterProperties is called. Reproduce the custom credentials-provider case with no refresh endpoint, then verify the AWS client can be created without the reported NullPointerException and add coverage in the relevant AWS properties tests.

Apache Iceberg version

1.11.0 (latest release)

Query engine

None

Please describe the bug 🐞

As of 1.11.0 (https://github.com/apache/iceberg/pull/15249), AwsClientProperties#credentialsProvider unconditionally does a clientCredentialsProviderProperties.put(VendedCredentialsProvider.URI, refreshCredentialsEndpoint) if "client.credentials-provider" is set; this may result in null being put into the properties map. Other similar code paths check first to make sure the value is not null or empty before putting the value.

This does not play well with custom credentials providers / org.apache.iceberg.aws.AwsClientProperties:

java.lang.NullPointerException
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at java.base/java.util.stream.Collectors.lambda$uniqKeysMapAccumulator$1(Collectors.java:180)
	at java.base/java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
	at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:179)
	at java.base/java.util.HashMap$EntrySpliterator.forEachRemaining(HashMap.java:1858)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
	at org.apache.iceberg.util.PropertyUtil.filterProperties(PropertyUtil.java:191)
	at org.apache.iceberg.aws.AwsClientProperties.<init>(AwsClientProperties.java:116)
	at io.deephaven.iceberg.util.DeephavenS3ClientCredentialsProvider.create(DeephavenS3ClientCredentialsProvider.java:29)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.apache.iceberg.common.DynMethods$UnboundMethod.invokeChecked(DynMethods.java:60)
	at org.apache.iceberg.common.DynMethods$UnboundMethod.invoke(DynMethods.java:73)
	at org.apache.iceberg.common.DynMethods$StaticMethod.invoke(DynMethods.java:186)
	at org.apache.iceberg.aws.AwsClientProperties.createCredentialsProvider(AwsClientProperties.java:314)
	at org.apache.iceberg.aws.AwsClientProperties.credentialsProvider(AwsClientProperties.java:296)
	at org.apache.iceberg.aws.AwsClientProperties.credentialsProvider(AwsClientProperties.java:218)
	at org.apache.iceberg.aws.s3.S3FileIOProperties.getCredentialsProvider(S3FileIOProperties.java:996)
	at org.apache.iceberg.aws.s3.S3FileIOProperties.applyCredentialConfigurations(S3FileIOProperties.java:985)
	at org.apache.iceberg.aws.AwsClientFactories$DefaultAwsClientFactory.lambda$s3$0(AwsClientFactories.java:116)
	at software.amazon.awssdk.utils.builder.SdkBuilder.applyMutation(SdkBuilder.java:61)
	at org.apache.iceberg.aws.AwsClientFactories$DefaultAwsClientFactory.s3(AwsClientFactories.java:115)
	at io.deephaven.iceberg.util.DeephavenAwsClientFactory.s3(DeephavenAwsClientFactory.java:49)

I'm unclear the exact semantics of nulls in property maps, and if this should be considered an upstream issue (ie, null should not be put in the map), or a downstream issue (AwsClientProperties should be tolerant of entries that have null values).

Willingness to contribute

• I can contribute a fix for this bug independently
• I would be willing to contribute a fix for this bug with guidance from the Iceberg community
• I cannot contribute a fix for this bug at this time