Why is namespace URL included in file spec for gradle-jaxb-plugin?

Trying to move from maven-jaxb2-plugin to gradle-jaxb-plugin.

Here is my script:

buildscript {

  repositories {
    jcenter()
    mavenCentral()
  }

  dependencies {
    classpath 'com.github.jacobono:gradle-jaxb-plugin:1.3.6'
  }
}

apply plugin: 'com.github.jacobono.jaxb'

dependencies {
  jaxb 'com.sun.xml.bind:jaxb-xjc:2.2.11'
  jaxb 'com.sun.xml.bind:jaxb-impl:2.2.11'
  jaxb 'javax.xml.bind:jaxb-api:2.2.11'
}

jaxb {
  xsdDir = "/commons/schemas/widgets/src/main/resources/v1"
}

gradle clean xjc
then results in:

Execution failed for task ':commons:schemas:widgets:xsd-dependency-tree'.
> java.io.FileNotFoundException: /development/project/commons/schemas/widgets/src/main/resources/v1/http:/ourjoint.com/schema/commons/v1 (No such file or directory)

Now then… any ideas why it wants to catenate the namespace URL onto this file location like that?

ls /development/project/commons/schemas/widgets/src/main/resources/v1/    

shows that this IS where the XSD’s are.

Hmm… this may be related to a catalog file. I’ve not been able to figure out how to specify to use one. Clue?

Something else. I note that classpath is often spec’d as:

dependencies {
  classpath 'com.github.jacobono.plugins:gradle-jaxb-plugin:1.3.6'
}

…but this doesn’t seem to be correct. If I use this, I get:

Could not find com.github.jacobono.plugins:gradle-jaxb-plugin:1.3.6.

I have the other issue when I use instead:

dependencies {
  classpath 'com.github.jacobono:gradle-jaxb-plugin:1.3.6'
}