Fix invalid paragraph nesting inside ODT headers causing XML parsing errors

[francoVV02]

Problem

When generating ODT documents with styled text (bold, italic, underline, etc.) inside headers, the ODTDocumentHandler incorrectly creates paragraph elements (<text:p>) inside header elements (<text:h>). This violates the ODT specification where both headers and paragraphs are block-level elements that cannot be nested.

Current Invalid Output

<text:h text:style-name="Heading_20_1" text:outline-level="1">
    <text:p><text:span text:style-name="XDocReport_Bold">Bold Header Text</text:span>
</text:h>
<!-- Missing </text:p> closing tag -->

Excpected Valid Output

<text:h text:style-name="Heading_20_1" text:outline-level="1">
    <text:span text:style-name="XDocReport_Bold">Bold Header Text</text:span>
</text:h>

Errors Caused

SAX Parser Exception when parsing the generated ODT:

org.xml.sax.SAXParseException: The element type "text:p" must be terminated by the matching end-tag "</text:p>"

ClassCastException during PDF conversion:

java.lang.ClassCastException: Insertion of illegal Element: 12
at com.lowagie.text.Phrase.add(Phrase.java:301)

Solution

Modified startParagraphIfNeeded in ODTDocumentHandler.java:

• Added check for insideHeader flag
• Prevents paragraph creation when inside header elements

Fixes #685