ZAP 2.4.0 throws HeadlessExceptions when running in daemon mode on headless machine

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What steps will reproduce the problem?
1. Run ZAP 2.4.0 on a headless machine invoked with -daemon
2. Make a test call via the zap.urlopen(target) API.
3. Note exception:

[ZAP-ProxyThread-2] ERROR HttpSender - 
No X11 DISPLAY variable was set, but this program performed an operation which 
requires it.
java.awt.HeadlessException: 
No X11 DISPLAY variable was set, but this program performed an operation which 
requires it.
    at sun.awt.HeadlessToolkit.getMenuShortcutKeyMask(HeadlessToolkit.java:234)
    at org.zaproxy.zap.extension.httpsessions.HttpSessionsPanel.initialize(Unknown Source)
    at org.zaproxy.zap.extension.httpsessions.HttpSessionsPanel.<init>(Unknown Source)
    at org.zaproxy.zap.extension.httpsessions.ExtensionHttpSessions.getHttpSessionsPanel(Unknown Source)
    at org.zaproxy.zap.extension.httpsessions.ExtensionHttpSessions.onHttpRequestSend(Unknown Source)
    at org.parosproxy.paros.network.HttpSender.notifyRequestListeners(Unknown Source)
    at org.parosproxy.paros.network.HttpSender.sendAndReceive(Unknown Source)
    at org.parosproxy.paros.network.HttpSender.sendAndReceive(Unknown Source)
    at org.parosproxy.paros.core.proxy.ProxyThread.processHttp(Unknown Source)
    at org.parosproxy.paros.core.proxy.ProxyThread.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)

ERROR PassiveScanThread - Scanner Parameter Scanner failed on record 1 from 
History table: GET http://demo.testfire.net
java.awt.HeadlessException: 
No X11 DISPLAY variable was set, but this program performed an operation which 
requires it.
    at sun.awt.HeadlessToolkit.getMenuShortcutKeyMask(HeadlessToolkit.java:234)
    at org.zaproxy.zap.extension.params.ParamsPanel.initialize(Unknown Source)
    at org.zaproxy.zap.extension.params.ParamsPanel.<init>(Unknown Source)
    at org.zaproxy.zap.extension.params.ExtensionParams.getParamsPanel(Unknown Source)
    at org.zaproxy.zap.extension.params.ExtensionParams.onHttpRequestSend(Unknown Source)
    at org.zaproxy.zap.extension.params.ParamScanner.scanHttpRequestSend(Unknown Source)
    at org.zaproxy.zap.extension.pscan.PassiveScanThread.run(Unknown Source)

This happens on many other calls as well. Because the task dies ZAP is unusable 
via headless API. First discovered trying to use http sessions via API - 
because the URLOpen task fails before completion no session is available for 
the site (and in fact no site is created).

What is the expected output? What do you see instead?
ZAP runs correctly in headless daemon mode as it did in 2.3.1.

What version of the product are you using? On what operating system?
ZAP 2.4.0, Linux

Please provide any additional information below.

Original issue reported on code.google.com by tbach0...@gmail.com on 28 Apr 2015 at 6:21

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Original comment by THC...@gmail.com on 28 Apr 2015 at 9:53

• Changed state: Accepted

[GoogleCodeExporter]

ZAP has been migrated to github

This issue will be on github issues with the same ID: 
https://github.com/zaproxy/zaproxy/issues

Original comment by psii...@gmail.com on 5 Jun 2015 at 9:18

• Changed state: Done