Allow XML components injection

**Cherry-pick to 5.0.x & 4.3.x**

* Polishing after rebase
* Copyright to 2019

* Rebase and update according upstream deps

spring-integration-xml/src/main/resources/org/springframework/integration/xml/config/spring-integration-xml-5.1.xsd

@@ -383,6 +383,22 @@
 							<xsd:union memberTypes="xsd:boolean xsd:string" />
 						</xsd:simpleType>
 					</xsd:attribute>
+					<xsd:attribute name="converter">
+						<xsd:annotation>
+							<xsd:documentation>
+								Specify the XmlPayloadConverter to use when converting a Message payload prior
+								to XPath evaluation.
+								The DefaultXmlPayloadConverter is used if this reference is not provided, and it
+								should be sufficient in most cases since it can convert from Node, Document, Source,
+								File, and String typed payloads.
+							</xsd:documentation>
+							<xsd:appinfo>
+								<tool:annotation kind="ref">
+									<tool:expected-type type="org.springframework.integration.xml.XmlPayloadConverter"/>
+								</tool:annotation>
+							</xsd:appinfo>
+						</xsd:annotation>
+					</xsd:attribute>
 				</xsd:extension>
 			</xsd:complexContent>
 		</xsd:complexType>