BUG: Enrich Data by Webservice - Web Mining : Does not pass 'request properties'

I am trying to access the MailChimp "Enrich Data by Webservice". 
After reading tons of Documentation I tried to check what is actually sent to compare it to a working Chrome REST extension test.
There it shows that the request properties are not sent to the server. Therefore no authentican can work, nor any other instructions.

This will also explain most of the similar discussions here in the forum.
This is the process: (Copies and pasted from the canvas) 

<?xml version="1.0" encoding="UTF-8"?><process version="7.6.001">
  <operator activated="true" class="operator_toolbox:create_exampleset_from_doc" compatibility="0.5.000" expanded="true" height="68" name="Create ExampleSet" width="90" x="45" y="136">
    <parameter key="Column Separator" value=","/>
    <parameter key="Input Csv" value="function&#10;lists"/>
  </operator>
</process>
<?xml version="1.0" encoding="UTF-8"?><process version="7.6.001">
  <operator activated="true" class="web:enrich_data_by_webservice" compatibility="7.3.000" expanded="true" height="68" name="Enrich Data by Webservice (2)" width="90" x="246" y="136">
    <parameter key="query_type" value="Regular Expression"/>
    <list key="string_machting_queries"/>
    <parameter key="attribute_type" value="Nominal"/>
    <list key="regular_expression_queries">
      <parameter key="output" value=".*"/>
    </list>
    <list key="regular_region_queries"/>
    <list key="xpath_queries"/>
    <list key="namespaces"/>
    <parameter key="ignore_CDATA" value="true"/>
    <parameter key="assume_html" value="true"/>
    <list key="index_queries">
      <parameter key="function" value="1.1"/>
    </list>
    <list key="jsonpath_queries"/>
    <parameter key="request_method" value="GET"/>
    <parameter key="url" value="http://us16.api.mailchimp.com/3.0/lists/"/>
    <parameter key="separator" value=";"/>
    <parameter key="delay" value="0"/>
    <list key="request_properties">
      <parameter key="authorization:" value="Bearer a2xsO.....................................zMTY="/>
      <parameter key="xyz:" value="abc"/>
    </list>
    <parameter key="encoding" value="UTF-8"/>
  </operator>
</process>

Neither the 'authorization' nor the 'xyz' are in the request as can be seen in the Wireshark trace:

Hypertext Transfer Protocol
    GET /3.0/lists/ HTTP/1.1\r\n
        [Expert Info (Chat/Sequence): GET /3.0/lists/ HTTP/1.1\r\n]
            [GET /3.0/lists/ HTTP/1.1\r\n]
            [Severity level: Chat]
            [Group: Sequence]
        Request Method: GET
        Request URI: /3.0/lists/
        Request Version: HTTP/1.1
    User-Agent: Java/1.8.0_141\r\n
    Host: us16.api.mailchimp.com\r\n
    Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2\r\n
    Connection: keep-alive\r\n
    \r\n
    [Full request URI: http://us16.api.mailchimp.com/3.0/lists/]
    [HTTP request 1/1]
    [Response in frame: 1989]

I am currently using RM 7.6.001