### Question:
Packages { public static String toClause(List<String> packages) { return Joiner.on(", ").skipNulls().join(packages); } private  Packages(); static String toClause(List<String> packages); static String getPackageName(String filePath); static boolean shouldBeExported(String packageName);  }### Answer:
@Test public void testToClause() throws Exception { assertThat(Packages.toClause(Collections.<String>emptyList())).isEmpty(); assertThat(Packages.toClause(ImmutableList.of("org.acme"))).contains("org.acme"); assertThat(Packages.toClause(ImmutableList.of("org.acme", "com.foo"))).contains("org.acme, com.foo"); }