Inefficient use of a for loop

[dlozaco]

problem

In the following directory: \cloudstack-main\core\src\main\java\org\apache\cloudstack\direct\download\HttpsDirectTemplateDowloader.java at line 101 we see this maybe inefficient use of a for loop:

for (String headerKey: headers.keySet()) {
    req.setHeader(headerKey, headers.get(headerKey));
}

Using this for loop for the entrySet in this way causes a drop in performance because using the method .get() after iterating a keySet() it's not worth it at all.

versions

4.20

The steps to reproduce the bug

What to do about it?

We found a better implementation using this:

for (Map.Entry<String, String> entry : headers.entrySet()) {
    req.setHeader(entry.getKey(), entry.getValue());
}

This avoids unnecessary searches, iterating and setting the values faster than the previous case.

[DaanHoogland]

feel free to submit a PR @dlozaco