strange behavior from esper when invoking methods on an Object variable while using a context

Demo.java

package com.apexclearing.esperdemo;

import com.espertech.esper.client.*;

import java.util.*;

public class Demo {
    private final static String[] demoStatements = new String[]{
            "  CREATE CONTEXT partcontext PARTITION BY part FROM msg"
            ,
            "  CREATE VARIABLE com.apexclearing.esperdemo.Demo demo = com.apexclearing.esperdemo.Demo.make()"
            ,
            "  CONTEXT partcontext\n" +
            "  SELECT *\n" +
            "  FROM PATTERN [\n" +
            "    EVERY (\n" +
            "      firstMsg=msg(\n" +
            "        demo.log(' init', part, filt, msgId)\n" +
            "      )\n" +
            "      -> (\n" +
            "        [1:] rest=msg(\n" +
            "          filt = firstMsg.filt\n" +
            "          AND demo.log(' rest', part, filt, msgId)\n" +
            "        )\n" +
            "        until (\n" +
            "          msg(\n" +
            "            filt != firstMsg.filt\n" +
            "            AND demo.log('until', part, filt, msgId)\n" +
            "          )\n" +
            "        )\n" +
            "      )\n" +
            "    )\n" +
            "  ]"
    };

    /**
     * Factory method so we can assign our variable in EPL
     */
    public static Demo make() {
        return new Demo();
    }

    /**
     * Demonstrates weird behavior when invoked from EPL
     */
    public boolean log(String from, String id, String filt, int msgId) {
        System.out.println("{ from: " + from + ", id: " + id + ", filt: " + filt + ", msgId: " + msgId + " }");
        return true;
    }

    public static void main(String[] args) throws Exception {
        Map<String, Object> schema = new HashMap<String, Object>();
        schema.put("part", String.class);
        schema.put("filt", String.class);
        schema.put("msgId", int.class);
        List<Map<String, Object>> events = new ArrayList<>();

        // part, filt, msgId
        events.add(makeEvent("foo", "y", 101));
        events.add(makeEvent("bar", "n", 102));
        events.add(makeEvent("bar", "y", 103));
        events.add(makeEvent("bar", "y", 104));
        events.add(makeEvent("bar", "n", 105));

        new DemoRunner(schema, demoStatements, events).run();
    }

    private static Map<String, Object> makeEvent(String part, String filt, int msgId) {
        Map<String, Object> event = new HashMap<>();
        event.put("part", part);
        event.put("filt", filt);
        event.put("msgId", msgId);
        return event;
    }

    private static class DemoRunner {
        private final EPServiceProvider provider;
        private final String[] statements;
        private final List<Map<String, Object>> events;

        public DemoRunner(Map<String, Object> schema, String[] statements, List<Map<String, Object>> events) {
            this.statements = statements;
            this.events = events;

            Configuration esperConfig = new Configuration();
            provider = EPServiceProviderManager.getProvider(UUID.randomUUID().toString(), esperConfig);

            ConfigurationOperations providerOptions = provider.getEPAdministrator().getConfiguration();
            providerOptions.addEventType("msg", schema);
        }

        private void run() throws Exception {
            EPRuntime epRuntime = provider.getEPRuntime();
            EPAdministrator epAdministrator = provider.getEPAdministrator();
            for (String stmt : statements) {
                epAdministrator.createEPL(stmt);
            }

            for (Map<String, Object> event : events) {
                epRuntime.sendEvent(event, "msg");
            }
        }
    }
}

output.txt

# we see a bunch of things that don't correspond to actual
# messages, and we keep seeing id: "foo" up until the end,
# despite the fact that he have matched only the firstMsg
# guy, in the "foo" context, and should never have appeared
# in the "bar" context.

{ from:  init, id: foo, filt: y, msgId: 101 }
{ from: until, id: foo, filt: n, msgId: 102 }
{ from: until, id: foo, filt: n, msgId: 102 }
{ from:  init, id: bar, filt: n, msgId: 102 }
{ from: until, id: bar, filt: y, msgId: 103 }
{ from:  rest, id: foo, filt: y, msgId: 103 }
{ from:  rest, id: foo, filt: y, msgId: 104 }
{ from:  init, id: bar, filt: y, msgId: 104 }
{ from: until, id: foo, filt: n, msgId: 105 }
{ from: until, id: bar, filt: n, msgId: 105 }