See following example:

import jdk.test.lib.process.ProcessTools;

public class Main {


    public static void main(String[] args) throws Exception {
        if (args.length > 0) {
            System.out.print(args[0]);
            return;
        }
        // Needed to set property if run without using jtreg.
        System.setProperty("test.jdk", "/Users/lmesnik/tools/jdk-19/macosx-x64");
        Process p1 = ProcessTools.startProcess("process",ProcessTools.createJavaProcessBuilder(Main.class.getName(), "ARG1"));
        p1.waitFor();

        System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");

        Process p2 = ProcessTools.startProcess("process",ProcessTools.createJavaProcessBuilder(Main.class.getName(), "ARG2\n"));
        p2.waitFor();

        System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");

        Process p3 = ProcessTools.startProcess("process",ProcessTools.createJavaProcessBuilder(Main.class.getName(), "ARG3\nARG3.1"));
        p3.waitFor();
    }
}

The output doesn't contain last line:
Command line: [/Users/lmesnik/tools/jdk-19/macosx-x64/bin/java -cp /Users/lmesnik/IdeaProjects/tests/out/production/tests Main ARG1 ]
[process]:/Users/lmesnik/tools/jdk-19/macosx-x64/bin/java -cp /Users/lmesnik/IdeaProjects/tests/out/production/tests Main ARG1
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Command line: [/Users/lmesnik/tools/jdk-19/macosx-x64/bin/java -cp /Users/lmesnik/IdeaProjects/tests/out/production/tests Main ARG2
 ]
[process]:/Users/lmesnik/tools/jdk-19/macosx-x64/bin/java -cp /Users/lmesnik/IdeaProjects/tests/out/production/tests Main ARG2

[process] ARG2
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Command line: [/Users/lmesnik/tools/jdk-19/macosx-x64/bin/java -cp /Users/lmesnik/IdeaProjects/tests/out/production/tests Main ARG3
ARG3.1 ]
[process]:/Users/lmesnik/tools/jdk-19/macosx-x64/bin/java -cp /Users/lmesnik/IdeaProjects/tests/out/production/tests Main ARG3
ARG3.1
[process] ARG3

Process finished with exit code 0