[BUG] ShardFailure hides real failure if ApiTypeHelper assertion fails

What is the bug?

Recently, we've experienced a shard failure that we could not get information about because the ShardFailure class asserts non-null on the shard property. See the stack trace:

org.opensearch.client.util.MissingRequiredPropertyException: Missing required property 'ShardFailure.shard'
	at org.opensearch.client.util.ApiTypeHelper.requireNonNull(ApiTypeHelper.java:90)
	at org.opensearch.client.opensearch._types.ShardFailure.<init>(ShardFailure.java:83)
	at org.opensearch.client.opensearch._types.ShardFailure.<init>(ShardFailure.java:61)
	at org.opensearch.client.opensearch._types.ShardFailure$Builder.build(ShardFailure.java:276)
	at org.opensearch.client.opensearch._types.ShardFailure$Builder.build(ShardFailure.java:179)
	at org.opensearch.client.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:98)
	at org.opensearch.client.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:60)
	at org.opensearch.client.json.JsonpDeserializerBase$ArrayDeserializer.deserialize(JsonpDeserializerBase.java:343)
	at org.opensearch.client.json.JsonpDeserializerBase$ArrayDeserializer.deserialize(JsonpDeserializerBase.java:308)
	at org.opensearch.client.json.JsonpDeserializer.deserialize(JsonpDeserializer.java:87)
	at org.opensearch.client.json.ObjectDeserializer$FieldObjectDeserializer.deserialize(ObjectDeserializer.java:81)
	at org.opensearch.client.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:185)
	at org.opensearch.client.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:146)
	at org.opensearch.client.json.JsonpDeserializer.deserialize(JsonpDeserializer.java:87)
	at org.opensearch.client.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:91)
	at org.opensearch.client.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:55)
	at org.opensearch.client.json.ObjectDeserializer$FieldObjectDeserializer.deserialize(ObjectDeserializer.java:81)
	at org.opensearch.client.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:185)
	at org.opensearch.client.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:146)
	at org.opensearch.client.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:97)
	at org.opensearch.client.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:60)
	at org.opensearch.client.json.JsonpDeserializerBase$ArrayDeserializer.deserialize(JsonpDeserializerBase.java:343)
	at org.opensearch.client.json.JsonpDeserializerBase$ArrayDeserializer.deserialize(JsonpDeserializerBase.java:308)
	at org.opensearch.client.json.JsonpDeserializer.deserialize(JsonpDeserializer.java:87)
	at org.opensearch.client.json.ObjectDeserializer$FieldObjectDeserializer.deserialize(ObjectDeserializer.java:81)
	at org.opensearch.client.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:185)
	at org.opensearch.client.json.ObjectDeserializer.deserialize(ObjectDeserializer.java:146)
	at org.opensearch.client.json.JsonpDeserializer.deserialize(JsonpDeserializer.java:87)
	at org.opensearch.client.json.ObjectBuilderDeserializer.deserialize(ObjectBuilderDeserializer.java:91)
	at org.opensearch.client.json.DelegatingDeserializer$SameType.deserialize(DelegatingDeserializer.java:55)
	at org.opensearch.client.transport.rest_client.RestClientTransport.decodeResponse(RestClientTransport.java:360)
	at org.opensearch.client.transport.rest_client.RestClientTransport.getHighLevelResponse(RestClientTransport.java:326)
	at org.opensearch.client.transport.rest_client.RestClientTransport.performRequest(RestClientTransport.java:148)
	at org.opensearch.client.opensearch.OpenSearchClient.bulk(OpenSearchClient.java:224)

How can one reproduce the bug?

It requires a shard failure with shard = null, which I don't know how to reproduce, since the client trips over the assert-non-null.

What is the expected behavior?

Communicating the real cause of the failure must be prioritized over ApiTypeHelper assertions.

What is your host/environment?

Linux, Ubuntu

opensearch 2.12.0

<dependency>
	<groupId>org.opensearch.client</groupId>
	<artifactId>opensearch-java</artifactId>
	<version>2.23.0</version>
</dependency>
<dependency>
	<groupId>org.opensearch.client</groupId>
	<artifactId>opensearch-rest-client</artifactId>
	<version>2.19.1</version>
</dependency>

Do you have any screenshots?

N/A

Do you have any additional context?

N/A

Start with org.opensearch.client.opensearch._types.ShardFailure and ApiTypeHelper.requireNonNull, following the deserialization path shown in the stack trace. Determine how a shard failure with a null shard is represented, then add coverage for that response and verify that the underlying failure information is preserved instead of being replaced by the assertion exception.