The CustomizationHandler interface (com.oracle.pgbu.gateway.customization.CustomizationHandler) provides the entry point into all of the Java code in the customization jar file and therefore must be implemented.
In the sample customization project, the Customization class (under com.mycompany.primavera.integration.custom package) implements the CustomizationHandler interface. The Gateway loads this class through reflection, and retrieves all other feature implementations by querying this class.
The Java class also must be defined in the XML description file. You can find the following at the top of the customization.xml from the sample customization project.
<JavaClassPath>com.mycompany.primavera.Customization</JavaClassPath>