The Javadoc for PrintStream.println(String) says "Prints a String and then terminate the line. This method behaves as though it invokes print(String) and then println()."

(Side note: there's a typo; "terminate" should be plural)

But that's now how it actually behaves. Instead, it behaves as if it invokes print(String) and then INVOKESPECIAL PrintStream.println().

Test case:

 import java.io.*;
    public class CrNlTest {
        public static void main(String[] args) throws Exception {
            try (PrintStream out = new PrintStream(System.out, true) {
                @Override
                public void println() {
                    this.print("***");
                    super.println();
                }
            }) {
    
                // Scenario 1
                out.println("test"); // outputs 74 65 73 74 0a
    
                // Scenario 2
                out.print("test"); // outputs 74 65 73 74 2a 2a 2a 0a
                out.println();
            }
        }
    }

Expected output:

test***
test***

Actual output:

test
test***