When a break element is defined in the middle of a Run, DocxFormatProvider imports it at the end of the same run. For example, the following content: 

<w:r>
  <w:t>This is</w:t>
  <w:br/>
  <w:t xml:space="preserve"> a simple sentence.</w:t>
</w:r>

Results in "This is a simple sentence " + break element after it.