@Override
        public String[] selectImports(AnnotationMetadata annotationMetadata) {
            if (!ClassUtils.isPresent("org.springframework.boot.autoconfigure.condition.ConditionalOnBean", null)) {
                return new String[0];
            }
            String className = annotationMetadata.getClassName();
            if (SingleDatabaseConfiguration.BEAN_NAME.equals(className)) {
                return new String[] { PrimaryDataSourceAutoConfiguration.class.getName() };
            }
            if (MultipleDatabasesConfiguration.BEAN_NAME.equals(className)) {
                return new String[] { PrimaryDataSourceAutoConfiguration.class.getName(), SecondaryDataSourceAutoConfiguration.class.getName() };
            }
            throw new IllegalStateException("Unexpected selector configuration class: " + className);
        }
Implementation of the {@link org.springframework.test.context.ContextCustomizerFactory} interface,
which is responsible for initialization of the embedded database and its registration to the application context.
The applied initialization strategy is driven by the {@link AutoConfigureEmbeddedDatabase} annotation.

@see AutoConfigureEmbeddedDatabase
embedded-database-spring-test/src/main/java/io/zonky/test/db/EmbeddedDatabaseContextCustomizerFactory.java