Expose checkbox field marker as 'hidden' to RequestDataValueProcessor

Issue: SPR-17147

(cherry picked from commit fa72186)

Author: jhoeller

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/form/CheckboxTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -233,7 +233,7 @@ protected int writeTagContent(TagWriter tagWriter) throws JspException {
 			tagWriter.writeAttribute("type", "hidden");
 			String name = WebDataBinder.DEFAULT_FIELD_MARKER_PREFIX + getName();
 			tagWriter.writeAttribute("name", name);
-			tagWriter.writeAttribute("value", processFieldValue(name, "on", getInputType()));
+			tagWriter.writeAttribute("value", processFieldValue(name, "on", "hidden"));
 			tagWriter.endTag();
 		}
 

spring-webmvc/src/main/java/org/springframework/web/servlet/tags/form/CheckboxesTag.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -242,7 +242,7 @@ protected int writeTagContent(TagWriter tagWriter) throws JspException {
 			tagWriter.writeAttribute("type", "hidden");
 			String name = WebDataBinder.DEFAULT_FIELD_MARKER_PREFIX + getName();
 			tagWriter.writeAttribute("name", name);
-			tagWriter.writeAttribute("value", processFieldValue(name, "on", getInputType()));
+			tagWriter.writeAttribute("value", processFieldValue(name, "on", "hidden"));
 			tagWriter.endTag();
 		}