Adding functionality to config preferred authschemeProvider

[RanVaknin]

Motivation and Context

Previously, when multiple auth schemes were available for an operation, the SDK would choose the first one defined in the service model. This PR implements the auth scheme preference configuration that allows users to specify their preferred authentication schemes in order of preference when multiple auth schemes are supported.

Example usage:

// Via client configuration in code
MyServiceClient client = MyServiceClient.builder()
    .authSchemeProvider(MyServiceAuthSchemeProvider.defaultProvider(Arrays.asList("sigv4", "sigv4a")))
    .build();


// Via JVM properties:
// in code
System.setProperty("aws.authSchemePreference", "sigv4,sigv4a");
// or as a cmd line argument
java -Daws.authSchemePreference=sigv4,sigv4a -jar your-application.jar

// Via Environment variable:
export AWS_AUTH_SCHEME_PREFERENCE=sigv4,sigv4a

// Via AWS config file (~/.aws/config):
[default]
auth_scheme_preference = sigv4,sigv4a

---

Modifications

• [Modified] client builders to read and apply auth scheme preferences

• [Modified] the auth scheme resolution logic to respect user preferences while maintaining backward compatibility

• [Added] AuthSchemePreferenceProvider class to resolve auth scheme preferences from various sources:

  • Client configuration
  • JVM system properties (aws.authSchemePreference)
  • Environment variables (AWS_AUTH_SCHEME_PREFERENCE)
  • AWS config file (auth_scheme_preference)

• [Added] code generation support through PreferredAuthSchemeProviderSpec to generate service-specific auth scheme providers

Testing

• AuthSchemePreferenceProviderTest verifies proper parsing of auth scheme preferences from different formats (spaces, tabs, etc.)

• PreferredAuthSchemeProviderTest to test the reordering of auth schemes according to preferences
  comprehensive test cases for preference resolution from multiple sources, verifying proper precedence:

• Stubbed functional test with mock services to verify the selected auth scheme matches the expected preference in actual requests

Dismissing to unblock the change since I'm OOTO.

[sonarqubecloud]

Quality Gate passed

Issues
18 New issues
0 Accepted issues

Measures
0 Security Hotspots
95.7% Coverage on New Code
0.1% Duplication on New Code

See analysis details on SonarQube Cloud