Introduce "server.servlet" configuration prefix

This commit refactors the `ServerProperties` property keys and
introduces a separate "server.servlet" namespace to isolate
servlet-specific properties from the rest.

Closes gh-8066

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -152,8 +152,6 @@ content into your application; rather pick only the properties that you need.
 	server.compression.mime-types= # Comma-separated list of MIME types that should be compressed. For instance `text/html,text/css,application/json`
 	server.compression.min-response-size= # Minimum response size that is required for compression to be performed. For instance 2048
 	server.connection-timeout= # Time in milliseconds that connectors will wait for another HTTP request before closing the connection. When not set, the connector's container-specific default will be used. Use a value of -1 to indicate no (i.e. infinite) timeout.
-	server.context-parameters.*= # Servlet context init parameters. For instance `server.context-parameters.a=alpha`
-	server.context-path= # Context path of the application.
 	server.display-name=application # Display name of the application.
 	server.max-http-header-size=0 # Maximum size in bytes of the HTTP message header.
 	server.error.include-stacktrace=never # When to include a "stacktrace" attribute.
@@ -162,12 +160,14 @@ content into your application; rather pick only the properties that you need.
 	server.jetty.acceptors= # Number of acceptor threads to use.
 	server.jetty.max-http-post-size=0 # Maximum size in bytes of the HTTP post or put content.
 	server.jetty.selectors= # Number of selector threads to use.
-	server.jsp-servlet.class-name=org.apache.jasper.servlet.JspServlet # The class name of the JSP servlet.
-	server.jsp-servlet.init-parameters.*= # Init parameters used to configure the JSP servlet
-	server.jsp-servlet.registered=true # Whether or not the JSP servlet is registered
 	server.port=8080 # Server HTTP port.
 	server.server-header= # Value to use for the Server response header (no header is sent if empty)
-	server.servlet-path=/ # Path of the main dispatcher servlet.
+	server.servlet.context-parameters.*= # Servlet context init parameters. For instance `server.servlet.context-parameters.a=alpha`
+	server.servlet.context-path= # Context path of the application.
+	server.servlet.jsp.class-name=org.apache.jasper.servlet.JspServlet # The class name of the JSP servlet.
+	server.servlet.jsp.init-parameters.*= # Init parameters used to configure the JSP servlet
+	server.servlet.jsp.registered=true # Whether or not the JSP servlet is registered
+	server.servlet.path=/ # Path of the main dispatcher servlet.
 	server.use-forward-headers= # If X-Forwarded-* headers should be applied to the HttpRequest.
 	server.session.cookie.comment= # Comment for the session cookie.
 	server.session.cookie.domain= # Domain for the session cookie.

spring-boot-docs/src/main/asciidoc/appendix-configuration-metadata.adoc

@@ -42,7 +42,7 @@ categorized under "hints":
 			"sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
 		},
 		{
-			"name": "server.servlet-path",
+			"name": "server.servlet.path",
 			"type": "java.lang.String",
 			"sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties",
 			"defaultValue": "/"
@@ -84,18 +84,18 @@ categorized under "hints":
 ----
 
 Each "`property`" is a configuration item that the user specifies with a given value.
-For example `server.port` and `server.servlet-path` might be specified in
+For example `server.port` and `server.servlet.path` might be specified in
 `application.properties` as follows:
 
 [source,properties,indent=0]
 ----
 	server.port=9090
-	server.servlet-path=/home
+	server.servlet.path=/home
 ----
 
 The "`groups`" are higher level items that don't themselves specify a value, but instead
 provide a contextual grouping for properties. For example the `server.port` and
-`server.servlet-path` properties are part of the `server` group.
+`server.servlet.path` properties are part of the `server` group.
 
 NOTE: It is not required that every "`property`" has a "`group`", some properties might
 just exist in their own right.
@@ -160,7 +160,7 @@ The JSON object contained in the `properties` array can contain the following at
 |`name`
 | String
 | The full name of the property. Names are in lowercase dashed form (e.g.
-  `server.servlet-path`). This attribute is mandatory.
+  `server.servlet.path`). This attribute is mandatory.
 
 |`type`
 | String
@@ -270,7 +270,7 @@ The JSON object contained in the `hints` array can contain the following attribu
 |`name`
 | String
 | The full name of the property that this hint refers to. Names are in lowercase dashed
-  form (e.g. `server.servlet-path`). If the property refers to a map (e.g.
+  form (e.g. `server.servlet.path`). If the property refers to a map (e.g.
   `system.contexts`) the hint either applies to the _keys_ of the map (`system.context.keys`)
    or the values (`system.context.values`). This attribute is mandatory.
 
@@ -495,14 +495,14 @@ provider supports these parameters:
 |===
 
 
-The meta-data snippet below corresponds to the standard `server.jsp-servlet.class-name`
+The meta-data snippet below corresponds to the standard `server.servlet.jsp.class-name`
 property that defines the `JspServlet` class name to use:
 
 [source,json,indent=0]
 ----
 	{"hints": [
 		{
-			"name": "server.jsp-servlet.class-name",
+			"name": "server.servlet.jsp.class-name",
 			"providers": [
 				{
 					"name": "class-reference",

spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -2117,9 +2117,9 @@ Actuator HTTP endpoints are only available for Spring MVC-based applications. If
 to use Jersey and still use the actuator you will need to enable Spring MVC (by depending
 on `spring-boot-starter-web`, for example). By default, both Jersey and the Spring MVC
 dispatcher servlet are mapped to the same path (`/`). You will need to change the path for
-one of them (by configuring `server.servlet-path` for Spring MVC or
+one of them (by configuring `server.servlet.path` for Spring MVC or
 `spring.jersey.application-path` for Jersey). For example, if you add
-`server.servlet-path=/system` into `application.properties`, the actuator HTTP endpoints
+`server.servlet.path=/system` into `application.properties`, the actuator HTTP endpoints
 will be available under `/system`.