If your extension of the DataSource.Provider class returns DataSource.AuthenticationCapability values that indicate support for authentication, the DataSource.Connection class is instantiated with a DataSource.ConnectionParams instance in the constructor.
The values in this class can appear in debug logs and can be accessed by users who have the “Author Apex” permission. If you require better security, we recommend that you specify named credentials instead of URLs as your Apex callout endpoints. Salesforce manages all authentication for Apex callouts that specify a named credential as the callout endpoint so that your code doesn’t have to.
The following are properties for ConnectionParams.
public String password {get; set;}
Type: String
public DataSource.IdentityType principalType {get; set;}
Type: DataSource.IdentityType
public String username {get; set;}
Type: String