The values that are returned by the DataSource.Provider class determine which settings are available in the external data source definition in Salesforce. To access the external data source definition from Setup, enter External Data Sources in the Quick Find box, then select External Data Sources.
The following are methods for Provider.
public List<DataSource.AuthenticationCapability> getAuthenticationCapabilities()
public List<DataSource.Capability> getCapabilities()
Type: List<DataSource.Capability>
public DataSource.Connection getConnection(DataSource.ConnectionParams connectionParams)
Type: DataSource.Connection