Fix code example callouts in reference manual

framework-docs/src/docs/asciidoc/web/webmvc.adoc

@@ -5144,6 +5144,7 @@ Controllers can add explicit support for HTTP caching. We recommended doing so,
 against conditional request headers. A controller can add an `ETag` header and `Cache-Control`
 settings to a `ResponseEntity`, as the following example shows:
 
+--
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
@@ -5176,6 +5177,7 @@ settings to a `ResponseEntity`, as the following example shows:
 				.body(book)
 	}
 ----
+--
 
 The preceding example sends a 304 (NOT_MODIFIED) response with an empty body if the comparison
 to the conditional request headers indicates that the content has not changed. Otherwise, the
@@ -5184,6 +5186,7 @@ to the conditional request headers indicates that the content has not changed. O
 You can also make the check against conditional request headers in the controller,
 as the following example shows:
 
+--
 [source,java,indent=0,subs="verbatim,quotes",role="primary"]
 .Java
 ----
@@ -5223,6 +5226,7 @@ as the following example shows:
 <1> Application-specific calculation.
 <2> The response has been set to 304 (NOT_MODIFIED) -- no further processing.
 <3> Continue with the request processing.
+--
 
 
 There are three variants for checking conditional requests against `eTag` values, `lastModified`