[BUG] Struct columns are returning null when querying Iceberg tables

[engechas]

What is the bug?
Iceberg table support was recently added. When querying tables that contain struct type columns, the values of these columns is being returned as null.

{
  "metadata": "null",
  "time": 1717691198000,
  "time_dt": "2024-06-06T16:26:38.000Z",
  "cloud": "null",
  "api": "null",
  "dst_endpoint": "null",
  "actor": "null",
  "http_request": "null",
  "src_endpoint": "null",
  "session": "null",
  "policy": "null",
  "resources": "null",
  "class_name": "API Activity",
  "class_uid": 6003,
  "category_name": "Application Activity",
  "category_uid": 6,
  "severity_id": 1,
  "severity": "Informational",
  "user": "null",
  "activity_name": "Invoke",
  "activity_id": 99,
  "type_uid": 600399,
  "type_name": "API Activity: Other",
  "status": "Success",
  "is_mfa": "null",
  "unmapped": "{REDACTED}",
  "accountid": "REDACTED",
  "region": "us-east-1",
  "observables": "null"
}

Schema for the table

{
            "Columns": [
                {
                    "Name": "metadata",
                    "Type": "struct<product:struct<version:string,name:string,vendor_name:string,feature:struct<name:string>>,uid:string,profiles:array<string>,version:string>"
                },
                {
                    "Name": "time",
                    "Type": "bigint"
                },
                {
                    "Name": "cloud",
                    "Type": "struct<region:string,provider:string>"
                },
                {
                    "Name": "api",
                    "Type": "struct<response:struct<error:string,message:string>,operation:string,version:string,service:struct<name:string>,request:struct<uid:string>>"
                },
                {
                    "Name": "dst_endpoint",
                    "Type": "struct<svc_name:string>"
                },
                {
                    "Name": "actor",
                    "Type": "struct<user:struct<type:string,name:string,uid:string,uuid:string,account_uid:string,credential_uid:string>,session:struct<created_time:bigint,mfa:boolean,issuer:string>,invoked_by:string,idp:struct<name:string>>"
                },
                {
                    "Name": "http_request",
                    "Type": "struct<user_agent:string>"
                },
                {
                    "Name": "src_endpoint",
                    "Type": "struct<uid:string,ip:string,domain:string>"
                },
                {
                    "Name": "resources",
                    "Type": "array<struct<uid:string,account_uid:string,type:string>>"
                },
                {
                    "Name": "class_name",
                    "Type": "string"
                },
                {
                    "Name": "class_uid",
                    "Type": "int"
                },
                {
                    "Name": "category_name",
                    "Type": "string"
                },
                {
                    "Name": "category_uid",
                    "Type": "int"
                },
                {
                    "Name": "severity_id",
                    "Type": "int"
                },
                {
                    "Name": "severity",
                    "Type": "string"
                },
                {
                    "Name": "user",
                    "Type": "struct<uid:string,uuid:string,name:string>"
                },
                {
                    "Name": "activity_name",
                    "Type": "string"
                },
                {
                    "Name": "activity_id",
                    "Type": "int"
                },
                {
                    "Name": "type_uid",
                    "Type": "int"
                },
                {
                    "Name": "type_name",
                    "Type": "string"
                },
                {
                    "Name": "status",
                    "Type": "string"
                },
                {
                    "Name": "status_id",
                    "Type": "int"
                },
                {
                    "Name": "mfa",
                    "Type": "boolean"
                },
                {
                    "Name": "unmapped",
                    "Type": "map<string,string>"
                }
            ],
            "Location": "REDACTED",
            "InputFormat": "org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat",
            "OutputFormat": "org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat",
            "Compressed": false,
            "NumberOfBuckets": 0,
            "SerdeInfo": {
                "SerializationLibrary": "org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe"
            },
            "SortColumns": [],
            "Parameters": {
                "partition_filtering.enabled": "true"
            },
            "StoredAsSubDirectories": false
        }

The same behavior is not seen when querying non-Iceberg tables. In those queries, the struct fields are successfully populated in the results.

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Create an iceberg table with struct columns
2. Run a query against this table
3. Validate struct columns are null

What is the expected behavior?
The struct columns should be successfully populated

What is your host/environment?

• OS: [e.g. iOS]
• Version [e.g. 22]
• Plugins

Do you have any screenshots?
If applicable, add screenshots to help explain your problem.

Do you have any additional context?
Add any other context about the problem.

[penghuo]

Test with vanilla EMR-S + Iceberg. struct filed return null value