ServletWebServerFactoryConfiguration is package private with public inner classes

[snicoll]

while browsing the code I noticed this inconsistency:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/ServletWebServerFactoryConfiguration.java

Line 68 in ad6859f

public static class EmbeddedTomcat {

We may want to add a rule for it in javaformat as well.

[wilkinsona]

EmbeddedJetty and EmbeddedUndertow have the same inconsistency.

[philwebb]

We should make them package private as well