Version Properties
The properties to control which API Level and SDK Platform Tools versions to use are located in the Classy Data and Classy Apps home directory pom.xml files. Classy Data has 3 SDK properties as highlighted :<android.plugin.version>4.5.0</android.plugin.version>
<android.platform.version>25</android.platform.version>
<android.sdk.version>7.1.1_r3</android.sdk.version>
<android.support.version>25.3.1</android.support.version>
<robolectric.version>3.3.2</robolectric.version>
<ormlite.version>5.0</ormlite.version>
<dagger.version>2.6.1</dagger.version>
...
</properties>
The android.platform.version and android.sdk.version refer to the SDK Platform in two different ways. The first is the API level and the second is the specific 3-part version and revision of the SDK Platform Tools package. The package name displayed in the SDK Manager shows the version and API level eg. "Android 6.0 (API 23)" indicates version "6.0.0" and API level of "23". The package revision is displayed in the "Rev." column of the "SDK Platform" item, which is "2" in this example:
android.platform.version = 23
android.sdk.version = 6.0.0_r2

Note that Android 4.4W breaks the convention on how the version is displayed in that the revision is included in the package name.
