initial testing work

guava/src/test/java/org/baeldung/guava/collections/GuavaCollectionsExamples.java

@@ -0,0 +1,34 @@
+package org.baeldung.guava.collections;
+
+import java.util.List;
+
+import org.junit.Test;
+
+import com.google.common.base.Function;
+import com.google.common.collect.Lists;
+
+public class GuavaCollectionsExamples {
+
+    @SuppressWarnings({ "unused", "unchecked" })
+    @Test
+    public final void whenCastingAllElementsOfACollectionToSubtype_thenCastIsOK() {
+        final class CastFunction<F, T extends F> implements Function<F, T> {
+            @Override
+            @SuppressWarnings("unchecked")
+            public final T apply(final F from) {
+                return (T) from;
+            }
+        }
+
+        final List<Number> originalList = Lists.newArrayList();
+        final List<Integer> selectedProductsQuick = (List<Integer>) (List<? extends Number>) originalList;
+        final List<Integer> selectedProducts = Lists.transform(originalList, new CastFunction<Number, Integer>());
+        System.out.println(selectedProducts);
+    }
+
+    @Test
+    public final void when_then() {
+
+    }
+
+}