Actually, because for compatibility reasons, the signature of a method, which is using varargs function(Object... args) is the equivalent of a method declared with an array function(Object[] args).

Therefore in order to pass and spread any collection to function which expects varargs, you need to transform it to the array:

import java.util.Arrays;
import java.util.stream.Stream;

public class MyClass {
  
  static void printMany(String ...elements) {
     Arrays.stream(elements).forEach(System.out::println);
  }
  
  public static void main(String[] args) {
    printMany("one", "two", "three");
    printMany(new String[]{"one", "two", "three"});
    printMany(Stream.of("one", "two", "three").toArray(String[]::new));
    printMany(Arrays.asList("foo", "bar", "baz").toArray(new String[3]));
  }
}

All these calls of printMany will print:

one

two

three

It's not exactly the same as spread operator, but in most cases, it's good enough.