fix: parameters encoding doesn't work for ALB when using Spring Cloud

[mbfreder]

Issue #, if available: #1279

Description of changes:

Added parameter decoding for ALB when using Spring Cloud.

Context:

When an ALB receives a request with URL-encoded query parameters, it passes those parameters to the Lambda function exactly as they were received, with the encoding intact. For example:

• Original URL: https://example.com/path?time=1970-01-01T00%3A00%3A00.004Z
• In the ALB event sent to Lambda: "time": "1970-01-01T00%3A00%3A00.004Z"

The %3A (representing :) remains encoded in the query parameter value.
This behavior differs from API Gateway, which automatically decodes URL-encoded query parameters before including them in the event object sent to Lambda functions.

Currently when we use the classic way of mapping request events to servlet requests, things work fine as the decoding of queryStringParameters is properly handled for ALB. However, when using the new Spring Cloud (AwsSpringHttpProcessingUtils), the parameters are not decoded. This PR fixes the issue.

Note: Ideally, this decoding logic should reside inside the ServerlessHttpServletRequest the same way it's done in AwsProxyHttpServletRequest

By submitting this pull request

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I confirm that I've made a best effort attempt to update all relevant documentation.

[vicheey]

Any particular reason to use 2 inline condition instead of a regular if (v1Request.getRequestSource() == RequestSource.ALB) statement?

[mbfreder]

I just think it's more readable/concise if we avoid the if else statement. Otherwise, we'll have to do something like:

String k;
String v;
if (v1Request.getRequestSource() == RequestSource.ALB) {
    k = decodeValueIfEncoded(entry.getKey());
    v = decodeValueIfEncoded(entry.getValue());
} else {
    k = entry.getKey();
    v = entry.getValue();
}
httpRequest.setParameter(k, v);