J2SE Version (please include all output from java -version flag):
Java Web Start 11.51.2.16
JRE-Version verwenden 1.8.0_51-b16 Java HotSpot(TM) Client VM

Both 1.8.0_66-ea-b02 and 1.8.0_60-b27

Does this problem occur on J2SE 6ux or 7ux? Yes / No (pick one)
Not tested.

Operating System Configuration Information (be specific):
* Windows 8.1
* Windows 10

Hardware Configuration Information (be specific):

Bug Description:
We receive the follow error in the console:
Insecure property: (jnlp.codebase, http://localhost:8080/url%20with-space/) specified in unsigned jnlp file will not be set.

As the result our program crash with NPE. If the value does not contain a %20 then it works. This is completely unexpected because the property is prefixed with "jnlp.". We do not have signed jnlp file but it should work with every value if the property name is prefixed with "jnlp.".

Steps to Reproduce (be specific):
The jnlp looks like:
<?xml version="1.0" encoding="utf-8"?>
<jnlp codebase="http://localhost:8080/url%20with-space/">
    <information>
        <title>App Title</title>
        <vendor>App Vendor</vendor>
    </information>
    <security>
        <all-permissions/>
    </security>
    <resources>
        <j2se version="1.7+" href="http://java.sun.com/products/autodl/j2se"/>
        <jar href="app.jar" main="true" download="eager"/>
        <property name="jnlp.codebase" value="http://localhost:8080/url%20with-space/"/>
    </resources>
    <application-desc main-class="AppMain">
        <argument>Cookie=JSESSIONID=1;SESSIONID=1</argument>
    </application-desc>
</jnlp>