Jdbc4SqlXmlHandler returns null as documented (instead of throwing NPE)

Issue: SPR-13782
(cherry picked from commit 78dad4cf)

spring-jdbc/src/main/java/org/springframework/jdbc/support/xml/Jdbc4SqlXmlHandler.java

 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -53,43 +53,55 @@ public class Jdbc4SqlXmlHandler implements SqlXmlHandler {
 
 	@Override
 	public String getXmlAsString(ResultSet rs, String columnName) throws SQLException {
-		return rs.getSQLXML(columnName).getString();
+		SQLXML xmlObject = rs.getSQLXML(columnName);
+		return (xmlObject != null ? xmlObject.getString() : null);
 	}
 
 	@Override
 	public String getXmlAsString(ResultSet rs, int columnIndex) throws SQLException {
-		return rs.getSQLXML(columnIndex).getString();
+		SQLXML xmlObject = rs.getSQLXML(columnIndex);
+		return (xmlObject != null ? xmlObject.getString() : null);
 	}
 
 	@Override
 	public InputStream getXmlAsBinaryStream(ResultSet rs, String columnName) throws SQLException {
-		return rs.getSQLXML(columnName).getBinaryStream();
+		SQLXML xmlObject = rs.getSQLXML(columnName);
+		return (xmlObject != null ? xmlObject.getBinaryStream() : null);
 	}
 
 	@Override
 	public InputStream getXmlAsBinaryStream(ResultSet rs, int columnIndex) throws SQLException {
-		return rs.getSQLXML(columnIndex).getBinaryStream();
+		SQLXML xmlObject = rs.getSQLXML(columnIndex);
+		return (xmlObject != null ? xmlObject.getBinaryStream() : null);
 	}
 
 	@Override
 	public Reader getXmlAsCharacterStream(ResultSet rs, String columnName) throws SQLException {
-		return rs.getSQLXML(columnName).getCharacterStream();
+		SQLXML xmlObject = rs.getSQLXML(columnName);
+		return (xmlObject != null ? xmlObject.getCharacterStream() : null);
 	}
 
 	@Override
 	public Reader getXmlAsCharacterStream(ResultSet rs, int columnIndex) throws SQLException {
-		return rs.getSQLXML(columnIndex).getCharacterStream();
+		SQLXML xmlObject = rs.getSQLXML(columnIndex);
+		return (xmlObject != null ? xmlObject.getCharacterStream() : null);
 	}
 
 	@Override
 	public Source getXmlAsSource(ResultSet rs, String columnName, Class<? extends Source> sourceClass) throws SQLException {
 		SQLXML xmlObject = rs.getSQLXML(columnName);
+		if (xmlObject == null) {
+			return null;
+		}
 		return (sourceClass != null ? xmlObject.getSource(sourceClass) : xmlObject.getSource(DOMSource.class));
 	}
 
 	@Override
 	public Source getXmlAsSource(ResultSet rs, int columnIndex, Class<? extends Source> sourceClass) throws SQLException {
 		SQLXML xmlObject = rs.getSQLXML(columnIndex);
+		if (xmlObject == null) {
+			return null;
+		}
 		return (sourceClass != null ? xmlObject.getSource(sourceClass) : xmlObject.getSource(DOMSource.class));
 	}
 

spring-jdbc/src/main/java/org/springframework/jdbc/support/xml/SqlXmlHandler.java

 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -112,7 +112,7 @@ public interface SqlXmlHandler {
 	 * database and driver.
 	 * @param rs the ResultSet to retrieve the content from
 	 * @param columnName the column name to use
-	 * @return the content as character stream
+	 * @return the content as character stream, or {@code null} in case of SQL NULL
 	 * @throws SQLException if thrown by JDBC methods
 	 * @see java.sql.ResultSet#getSQLXML
 	 * @see java.sql.SQLXML#getCharacterStream
@@ -126,7 +126,7 @@ public interface SqlXmlHandler {
 	 * database and driver.
 	 * @param rs the ResultSet to retrieve the content from
 	 * @param columnIndex the column index to use
-	 * @return the content as character stream
+	 * @return the content as character stream, or {@code null} in case of SQL NULL
 	 * @throws SQLException if thrown by JDBC methods
 	 * @see java.sql.ResultSet#getSQLXML
 	 * @see java.sql.SQLXML#getCharacterStream
@@ -141,7 +141,7 @@ public interface SqlXmlHandler {
 	 * @param rs the ResultSet to retrieve the content from
 	 * @param columnName the column name to use
 	 * @param sourceClass the implementation class to be used
-	 * @return the content as character stream
+	 * @return the content as character stream, or {@code null} in case of SQL NULL
 	 * @throws SQLException if thrown by JDBC methods
 	 * @see java.sql.ResultSet#getSQLXML
 	 * @see java.sql.SQLXML#getSource
@@ -156,7 +156,7 @@ public interface SqlXmlHandler {
 	 * @param rs the ResultSet to retrieve the content from
 	 * @param columnIndex the column index to use
 	 * @param sourceClass the implementation class to be used
-	 * @return the content as character stream
+	 * @return the content as character stream, or {@code null} in case of SQL NULL
 	 * @throws SQLException if thrown by JDBC methods
 	 * @see java.sql.ResultSet#getSQLXML
 	 * @see java.sql.SQLXML#getSource