Java Api for Start Process Signature variables

Yes there is indeed internal API to do this. The following example shows how to read process (IProcess) from a project and use the process model API to play with instances of RequestStart.

package com.axonivy.demo;

import java.util.List;
import java.util.Set;

import ch.ivyteam.ivy.environment.EnvironmentNotAvailableException;
import ch.ivyteam.ivy.environment.Ivy;
import ch.ivyteam.ivy.persistence.PersistencyException;
import ch.ivyteam.ivy.process.IProcess;
import ch.ivyteam.ivy.process.model.element.event.start.RequestStart;
import ch.ivyteam.ivy.resource.datamodel.ResourceDataModelException;

public class Startables {

    public static void logStarts() throws Exception
    {
        Set<IProcess> allProcessInMyProject = Ivy.request().getProject().getProcesses(null);
        for(IProcess proc : allProcessInMyProject)
        {
            List<RequestStart> starts = proc.getModel().search().type(RequestStart.class)
                .and(start -> start.isStartByHttpRequestAllowed())
                .findDeep();
            starts.stream().forEach(Startables::log);
        }
    }

    private static void log(RequestStart start)
    {
        Ivy.log().info(start.getRequestPath().getLinkName()+" /signature="+start.getSignature().toSignatureString());
    }
}