The Teiid Designer in JBDS 8.x lets you create a connection to Salesforce and provides an option to define a custom URL if its different from the default one.

After the metadata for one or more tables have been imported, if one chooses to do a 'Preview Data' on one of the tables imported. There are issues as the Preview version of the resource adapter is missing the following URL config property and attempts to connect to the default/implicit SF URL.

<config-property type="java.lang.String" name="URL"></config-property>