Add a null check in ProxyConfiguration to avoid a NullPointerException when calling toBuilder

[debora-ito]

Motivation and Context

Fixes #2884

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed
• A short description of the change has been added to the CHANGELOG
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license

[joviegas]

If we force the Null Value to be assigned as Empty set then it might break the below code

aws-sdk-java-v2/http-clients/apache-client/src/main/java/software/amazon/awssdk/http/apache/ProxyConfiguration.java

Lines 131 to 145 in 584ccb5

	/**
	* The hosts that the client is allowed to access without going through the proxy.
	*
	* If the value is not set on the object, the value represent by "http.nonProxyHosts" system property is returned.
	* If system property is also not set, an unmodifiable empty set is returned.
	*
	* @see Builder#nonProxyHosts(Set)
	*/
	public Set<String> nonProxyHosts() {
	Set<String> hosts = nonProxyHosts == null && useSystemPropertyValues ? parseNonProxyHostsProperty()
	: nonProxyHosts;
	return Collections.unmodifiableSet(hosts != null ? hosts : Collections.emptySet());
	}

Here we do a null check on nonProxyHosts , if user set the value of nonProxyHosts as null internally we changing it to Collections.emptySet() might affect the getter public Set<String> nonProxyHosts()

Why don't we just do something s below

        @Override
        public Builder nonProxyHosts(Set<String> nonProxyHosts) {
            this.nonProxyHosts = nonProxyHosts != null ? new HashSet<>(nonProxyHosts) : null;
            return this;
        }

[sonarqubecloud]

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0 Bugs
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0 Security Hotspots
1 Code Smell

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0.0% Duplication