Aws Sdk Java V2 Core

# AWS SDK for Java 2.x API Reference

## Core Client Classes

### AwsClient
Base interface for all AWS service clients.

```java
public interface AwsClient extends AutoCloseable {
    // Base client interface
}
```

### SdkClient
Enhanced client interface with SDK-specific features.

```java
public interface SdkClient extends AwsClient {
    // Enhanced client methods
}
```

## Client Builders

### ClientBuilder
Base builder interface for all AWS service clients.

**Key Methods:**
- `region(Region region)` - Set AWS region
- `credentialsProvider(CredentialsProvider credentialsProvider)` - Configure authentication
- `overrideConfiguration(ClientOverrideConfiguration overrideConfiguration)` - Override default settings
- `httpClient(HttpClient httpClient)` - Specify HTTP client implementation
- `build()` - Create client instance

## Configuration Classes

### ClientOverrideConfiguration
Controls client-level configuration including timeouts and metrics.

**Key Properties:**
- `apiCallTimeout(Duration)` - Total timeout for all retry attempts
- `apiCallAttemptTimeout(Duration)` - Timeout per individual attempt
- `retryPolicy(RetryPolicy)` - Retry behavior configuration
- `metricPublishers(MetricPublisher...)` - Enable metrics collection

### Builder Example

```java
ClientOverrideConfiguration config = ClientOverrideConfiguration.builder()
    .apiCallTimeout(Duration.ofSeconds(30))
    .apiCallAttemptTimeout(Duration.ofSeconds(10))
    .addMetricPublisher(CloudWatchMetricPublisher.create())
    .build();
```

## HTTP Client Implementations

### ApacheHttpClient
Synchronous HTTP client with advanced features.

**Builder Configuration:**
- `maxConnections(Integer)` - Maximum concurrent connections
- `connectionTimeout(Duration)` - Connection establishment timeout
- `socketTimeout(Duration)` - Socket read/write timeout
- `connectionTimeToLive(Duration)` - Connection lifetime
- `proxyConfiguration(ProxyConfiguration)` - Proxy settings

### NettyNioAsyncHttpClient
Asynchronous HTTP client for high-performance applications.

**Builder Configuration:**
- `maxConcurrency(Integer)` - Maximum concurrent operations
- `connectionTimeout(Duration)` - Connection timeout
- `readTimeout(Duration)` - Read operation timeout
- `writeTimeout(Duration)` - Write operation timeout
- `sslProvider(SslProvider)` - SSL/TLS implementation

### UrlConnectionHttpClient
Lightweight HTTP client using Java's URLConnection.

**Builder Configuration:**
- `socketTimeout(Duration)` - Socket timeout
- `connectTimeout(Duration)` - Connection timeout

## Authentication and Credentials

### Credential Providers

#### EnvironmentVariableCredentialsProvider
Reads credentials from environment variables.

```java
CredentialsProvider provider = EnvironmentVariableCredentialsProvider.create();
```

#### SystemPropertyCredentialsProvider
Reads credentials from Java system properties.

```java
CredentialsProvider provider = SystemPropertyCredentialsProvider.create();
```

#### ProfileCredentialsProvider
Reads credentials from AWS configuration files.

```java
CredentialsProvider provider = ProfileCredentialsProvider.create("profile-name");
```

#### StaticCredentialsProvider
Provides static credentials (not recommended for production).

```java
AwsBasicCredentials credentials = AwsBasicCredentials.create("key", "secret");
CredentialsProvider provider = StaticCredentialsProvider.create(credentials);
```

#### DefaultCredentialsProvider
Implements the default credential provider chain.

```java
CredentialsProvider provider = DefaultCredentialsProvider.create();
```

### SSO Authentication

#### AwsSsoCredentialsProvider
Enables SSO-based authentication.

```java
AwsSsoCredentialsProvider ssoProvider = AwsSsoCredentialsProvider.builder()
    .ssoProfile("my-sso-profile")
    .build();
```

## Error Handling Classes

### SdkClientException
Client-side exceptions (network, timeout, configuration issues).

```java
try {
    awsOperation();
} catch (SdkClientException e) {
    // Handl