This commit is part of Jira issue: INT-2186 Please see for reference: https://jira.springsource.org/browse/INT-2186 Several sub-issues are affected: * INT-2137 - Add documentation for XPath Filter * INT-2138 - Add documentation for XML Validating Filter * INT-1917 - Document combination of SpEL and XPath expressions * INT-2187 - Add documentation for xpath-header-enricher