[Internal] Add HostType to HostMetadata

[tanmay-db]

🥞 Stacked PR

• hosttype-metadata [Files changed]
  • default-oidc-audience [Files changed]
    • hosttype-resolved [Files changed]

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Summary

Parses the host_type field from the /.well-known/databricks-config discovery endpoint into
HostMetadata and stores it on DatabricksConfig, so the SDK knows whether a host is a
workspace, account, or unified host without parsing hostnames.

Why

Today, getHostType() infers the host type by prefix-matching the hostname against
accounts. — everything else is classified as WORKSPACE. This cannot detect unified hosts,
which share the same hostname pattern as workspace hosts.

The server-side host_type field is being added to the /.well-known/databricks-config
endpoint, returning "workspace", "account", or "unified". This PR threads that value
into the SDK so it's available for use when getHostType() is updated to prefer
endpoint-resolved values over URL-based inference (PR #749).

What changed

Interface changes

• HostType.fromApiValue(String) — new static method that normalizes API values
  (workspace, account, unified) to enum constants (WORKSPACE, ACCOUNTS, UNIFIED).
  Case-insensitive. Returns null for unknown values.
• HostMetadata.getHostType() — new getter for the host_type field parsed from the
  discovery endpoint response.

Behavioral changes

• resolveHostMetadata() now populates DatabricksConfig.resolvedHostType from the discovery
  endpoint if not already set. getHostType() is not yet modified to use this value — that
  is PR [Internal] Use resolved host type from host metadata in getHostType() #749 in this stack.

Internal changes

• DatabricksConfig.resolvedHostType (package-private) stores the host type resolved during
  resolveHostMetadata().
• DatabricksConfig.getResolvedHostType() / setResolvedHostType() — package-private
  accessor for testing.

How is this tested?

• HostTypeTest — 7 tests for fromApiValue() normalization (all cases, case-insensitive,
  null, empty, unknown values)
• DatabricksConfigTest — 5 tests for host type resolution from metadata (populates
  workspace/account/unified, does not overwrite existing, unknown ignored)

NO_CHANGELOG=true

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Inputs:

• PR number: 747
• Commit SHA: dff706f0a48511e44fefdc8a46d6631c008b5dfb

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