[#1563] add PicocliSpringFactory constructor that takes a specified f…

…allback IFactory

picocli-spring-boot-starter/src/main/java/picocli/spring/PicocliSpringFactory.java

@@ -5,16 +5,46 @@
 import org.springframework.context.ApplicationContext;
 import picocli.CommandLine;
 
+import java.util.Objects;
+
 /**
+ * PicocliSpringFactory is a {@link picocli.CommandLine.IFactory} implementation that
+ * looks up classes in a given {@code org.springframework.context.ApplicationContext}.
+ * This allows picocli subcommands (and other objects that are instantiated as needed)
+ * to have {@code javax.inject} annotations that will be populated
+ * by Spring's dependency injection framework.
+ *
  * @author Thibaud Leprêtre
+ * @since 4.0.0
  */
 public class PicocliSpringFactory implements CommandLine.IFactory {
     private static final Logger logger = LoggerFactory.getLogger(PicocliSpringFactory.class);
 
     private final ApplicationContext applicationContext;
+    private final CommandLine.IFactory fallbackFactory;
 
+    /**
+     * Constructs a PicocliSpringFactory with the specified Application context,
+     * and picocli's {@link CommandLine#defaultFactory() default factory} as the fallback factory
+     * for classes not found in the application context.
+     * @param applicationContext the application context to look up classes in; must be non-{@code null}
+     */
     public PicocliSpringFactory(ApplicationContext applicationContext) {
-        this.applicationContext = applicationContext;
+        this(applicationContext, CommandLine.defaultFactory());
+    }
+
+    /**
+     * Constructs a PicocliSpringFactory with the specified Application context,
+     * and the specified fallback factory
+     * for classes not found in the application context.
+     * @param applicationContext the application context to look up classes in; must be non-{@code null}
+     * @param fallbackFactory the factory used to instantiate classes that are
+     *                        not found in the specified application context; must be non-{@code null}
+     * @since 4.7.0
+     */
+    public PicocliSpringFactory(ApplicationContext applicationContext, CommandLine.IFactory fallbackFactory) {
+        this.applicationContext = Objects.requireNonNull(applicationContext, "applicationContext");
+        this.fallbackFactory = Objects.requireNonNull(fallbackFactory, "fallbackFactory");
     }
 
     @Override
@@ -23,7 +53,7 @@ public <K> K create(Class<K> clazz) throws Exception {
             return getBeanOrCreate(clazz);
         } catch (Exception e) {
             logger.warn("Unable to get bean of class {}, using default Picocli factory", clazz);
-            return CommandLine.defaultFactory().create(clazz);
+            return fallbackFactory.create(clazz);
         }
     }