How to name packages in Java?

[mrkn]

There is no package naming convention in Java style guide.
I want to know how to name packages with two or more words.

Which of these is better?

• com.cookpad.fooBarBaz
• com.cookpad.FooBarBaz
• com.cookpad.foo_bar_baz
• com.cookpad.foobarbaz

[sys1yagi]

I'm almost use the following styles.

com.cookpad.foobarbaz

Google Java Style also recommends this style.