Add a srcjar example/test

Author: antonsviridov-src

examples/bazel-example/src/main/java/srcjar_example/BUILD

@@ -0,0 +1,13 @@
+genrule(
+    name = "generated-srcjar",
+    outs = ["sources.srcjar"],
+    cmd = "echo 'package com.testing; public class Bar {};' > Bar.java && jar cf $(@) Bar.java",
+)
+
+java_library(
+    name = "testing",
+    srcs = [
+        "Foo.java",
+        ":generated-srcjar",
+    ],
+)

examples/bazel-example/src/main/java/srcjar_example/Foo.java

@@ -0,0 +1,8 @@
+// testing/Foo.java
+package com.testing;
+
+public class Foo {
+    public Bar foo(Bar value) {
+        return value;
+    }
+}