Why the ivy.xml generated by `sbt publishLocal` has no configuration `default`?

Question

When I run sbt publishLocal on a sbt project, and found the generated ivy.xml is like this:

<?xml version="1.0" encoding="UTF-8"?>
<ivy-module version="2.0" xmlns:e="http://ant.apache.org/ivy/extra">
    <info organisation="com.thoughtworks" module="pact-jvm-provider-spring-mvc_2.11" revision="0.1" status="release" publication="20150225152253">
        <description>
        pact-jvm-provider-spring-mvc
        </description>
    </info>
    <configurations>
        <conf name="compile" visibility="public" description=""/>
        <conf name="runtime" visibility="public" description="" extends="compile"/>
        <conf name="test" visibility="public" description="" extends="runtime"/>
        <conf name="provided" visibility="public" description=""/>
        <conf name="optional" visibility="public" description=""/>

        <conf name="sources" visibility="public" description=""/>
        <conf name="docs" visibility="public" description=""/>
        <conf name="pom" visibility="public" description=""/>

    </configurations>
    <publications>
        <artifact name="pact-jvm-provider-spring-mvc_2.11" type="pom" ext="pom" conf="pom"/>
        <artifact name="pact-jvm-provider-spring-mvc_2.11" type="jar" ext="jar" conf="compile"/>
        <artifact name="pact-jvm-provider-spring-mvc_2.11" type="src" ext="jar" conf="sources" e:classifier="sources"/>
        <artifact name="pact-jvm-provider-spring-mvc_2.11" type="doc" ext="jar" conf="docs" e:classifier="javadoc"/>
    </publications>

    <dependencies>
        <dependency org="org.scala-lang" name="scala-library" rev="2.11.0" conf="compile->default(compile)"/>
        <dependency org="au.com.dius" name="pact-jvm-model_2.11" rev="2.1.11" conf="compile->default(compile)"/>
        <dependency org="au.com.dius" name="pact-jvm-consumer-junit_2.11" rev="2.1.10" conf="compile->default(compile)"/>
        <dependency org="org.springframework" name="spring-test" rev="4.1.3.RELEASE" conf="compile->default(compile)"/>
        <dependency org="org.springframework" name="spring-webmvc" rev="4.1.3.RELEASE" conf="compile->default(compile)"/>
        <dependency org="org.springframework" name="spring-context" rev="4.1.3.RELEASE" conf="compile->default(compile)"/>
        <dependency org="org.springframework" name="spring-core" rev="4.1.3.RELEASE" conf="compile->default(compile)"/>
        <dependency org="junit" name="junit" rev="4.12" conf="compile->default(compile)"/>
        <dependency org="javax.servlet" name="javax.servlet-api" rev="3.0.1" conf="compile->default(compile)"/>
        <dependency org="org.mockito" name="mockito-core" rev="1.9.5" conf="compile->default(compile)"/>
        <dependency org="org.specs2" name="specs2_2.11" rev="2.4.2" conf="test->default(compile)"/>
    </dependencies>
</ivy-module>

You can see all the dependencies are using configuration compile or test, rather than default, and there is no default configuration there.

So when I want to use it from another project, I have to specify the compile configuration explicitly like this:

compile group: "com.thoughtworks", name: "pact-jvm-provider-spring-mvc_2.11", version: "0.1", configuration: 'compile'

Instead of the simple one:

compile "com.reagroup:pact-jvm-provider-spring-mvc_2.11:0.1"

I check some other libraries and they all declared default and use that as default.

So my question is why sbt publishLocal will generate a ivy.xml without default configuration?