Fixed typo in javadoc on HttpRequestHandler

org.springframework.web/src/main/java/org/springframework/web/HttpRequestHandler.java

@@ -26,7 +26,7 @@ import javax.servlet.http.HttpServletResponse;
  * Plain handler interface for components that process HTTP requests,
  * analogous to a Servlet. Only declares {@link javax.servlet.ServletException}
  * and {@link java.io.IOException}, to allow for usage within any
- * {@link javax.servlet.http.HttpServlet}}. This interface is ssentially the
+ * {@link javax.servlet.http.HttpServlet}}. This interface is essentially the
  * direct equivalent of an HttpServlet, reduced to a central handle method.
  *
  * <p>The easiest way to expose an HttpRequestHandler bean in Spring style