Create a catalog and register an Iceberg table in Apache Polaris via its REST API

Verified steps

1. Start an Apache Polaris server (OSS version uses in-memory or PostgreSQL persistence); authenticate using the root credentials configured at startup to obtain a bearer token via POST /api/catalog/v1/oauth/tokens with grant_type=client_credentials
2. Create a catalog via POST /api/management/v1/catalogs with a JSON body specifying name, type (INTERNAL or EXTERNAL), storageConfigInfo (e.g., S3 bucket base location and IAM role ARN for credential vending), and default-base-location
3. Create a namespace within the catalog using the Iceberg REST spec endpoint POST /api/catalog/v1/{catalog_name}/namespaces with body {"namespace": ["my_namespace"], "properties": {}}
4. Register a table via POST /api/catalog/v1/{catalog_name}/namespaces/{namespace}/tables with a CreateTableRequest JSON body containing the schema (list of fields with id, name, type), partition spec, and location; Polaris returns a LoadTableResult with the metadata file location
5. Connect an engine such as Apache Spark using the SparkSessionExtensions and setting spark.sql.catalog.my_catalog to org.apache.iceberg.spark.SparkCatalog with catalog-impl=org.apache.iceberg.rest.RESTCatalog and uri pointing to your Polaris server URL