[BUG] Unable to set a custom AWSCredentialsProvider instance

What is the bug?
In the examples, the following code is given to illustrate using a custom AWSCredentialsProvider instance with the driver:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;


String url = "jdbc:opensearch://https://remote-host-name";

Properties properties = new Properties();
properties.put("awsCredentialsProvider", new EnvironmentVariableCredentialsProvider());

Connection con = DriverManager.getConnection(url, properties);
Statement st = con.createStatement();

// use the connection

// close connection
con.close();

However, in practice this causes a null pointer exception in the setProperties function of the org.opensearch.jdbc.config.ConnectionConfig.Builder class because the getProperty method is used, which returns null if the property value is not a string. If a string is specified instead, a org.opensearch.jdbc.config.ConnectionPropertyException exception is thrown because it's expecting an AWSCredentialsProvider instance and not a string.

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Implement the custom AWSCredentialsProvider example

What is the expected behavior?
The AWSCredentialsProvider instance should be correctly passed through to the driver.

What is your host/environment?

• OS: Manjaro Linux x86_64 (Kernel 6.1.71-1-MANJARO)
• JDK: 11

Start in org.opensearch.jdbc.config.ConnectionConfig.Builder.setProperties, focusing on how the awsCredentialsProvider property is retrieved and validated. Reproduce the documented custom AWSCredentialsProvider example with DriverManager.getConnection. Done means the provider instance is passed through without a NullPointerException or ConnectionPropertyException.