Add example of subquery (#171)

Author: gscheibel

example/src/main/kotlin/com/expedia/graphql/sample/query/SubQueries.kt

@@ -0,0 +1,31 @@
+package com.expedia.graphql.sample.query
+
+import com.expedia.graphql.annotations.GraphQLDescription
+import com.expedia.graphql.annotations.GraphQLIgnore
+import org.springframework.beans.factory.BeanFactory
+import org.springframework.beans.factory.BeanFactoryAware
+import org.springframework.beans.factory.getBean
+import org.springframework.context.annotation.Scope
+import org.springframework.stereotype.Component
+
+@Component
+class SubQueries: Query, BeanFactoryAware {
+    private lateinit var beanFactory: BeanFactory
+
+    @GraphQLIgnore
+    override fun setBeanFactory(beanFactory: BeanFactory) {
+        this.beanFactory = beanFactory
+    }
+
+    @GraphQLDescription(
+        """Creates a hierarchy of executable fields.
+        Arguments can be passed from `main` to the `SubQuery` via the constructor invoke by the bean factory"""
+    )
+    fun main(): SubQuery = beanFactory.getBean()
+}
+
+@Component
+@Scope("prototype")
+class SubQuery {
+    fun secondary() = "secondary"
+}