The Working With Derby section http://db.apache.org/derby/docs/dev/workingwithderby/twwdactivity4.html is missing some text: a coded <title> tag, "Running the client program," disappears from the output.
This happens because the source file twwdactivity4.dita plays tricks with DITA to try to get three subsections into a task topic, which does not allow subsections. The last of the intended subsection titles fails to appear in the output because it is coded as a second <title> element in an <example>, which can have only one <title>. (Ant warns about this during processing.) And the two titles that do appear are different sizes because one is an example title and the other just a paragraph in bold text.
To be valid DITA, this topic should be coded as a three-step task, where each step has a series of substeps. I have taken the liberty of doing this. I have also taken the liberty of correcting the punctuation and syntax problems that I found. I am attaching a proposed patch. It looks pretty hairy because of all the changes, I'm afraid. However, it is now valid DITA and shows the task steps clearly. I am attaching the output that results, for comparison with the original so you can see the substance is the same.