The <cxxClassDeclarationFile> element is defined within <cxxClassAPIItemLocation>. <cxxClassDeclarationFile> specifies the file in which the API declaration is present.
The element <cxxClassDeclarationFile> is empty but for the required attributes name and value. name is always "filePath" and value is the actual file path.
<cxxClassAPIItemLocation>
<cxxClassDeclarationFile name="filePath" value="D:/include/headerfile.h"/>
<cxxClassDeclarationFileLine name="lineNumber" value="775"/>
<cxxClassDefinitionFile name="filePath" value="D:/include/headerfile.h"/>
<cxxClassDefinitionFileLineStart name="lineNumber" value="765"/>
<cxxClassDefinitionFileLineEnd name="lineNumber" value="787"/>
</cxxClassAPIItemLocation>