Field#isType(Class<?> type) method should check if class is part of java.lang package

Currently, Field#isType(Class<?> type) method checks if there is an import for the given type (only in some case). If the given class represents a wrapper type like Boolean this will cause the following test to fail (the java.lang import is not needed):

JavaClass fooClass = create(JavaClass.class)
     .setPackage("com.test")
     .setName("Foo");

Field<JavaClass> property = fooClass.addField("private Boolean bar;");
assertTrue(property.isType(Boolean.class));