Improve PasswordEncoder deprecated notices

Fixes: gh-5296

core/src/main/java/org/springframework/security/core/userdetails/User.java

@@ -326,6 +326,8 @@ public class User implements UserDetails, CredentialsContainer {
 	 * @deprecated Using this method is not considered safe for production, but is
 	 * acceptable for demos and getting started. For production purposes, ensure the
 	 * password is encoded externally. See the method Javadoc for additional details.
+	 * There are no plans to remove this support. It is deprecated to indicate
+	 * that this is considered insecure for production purposes.
 	 */
 	@Deprecated
 	public static UserBuilder withDefaultPasswordEncoder() {

crypto/src/main/java/org/springframework/security/crypto/password/LdapShaPasswordEncoder.java

@@ -39,7 +39,8 @@ import java.util.Base64;
  * @deprecated Digest based password encoding is not considered secure. Instead use an
  * adaptive one way funciton like BCryptPasswordEncoder, Pbkdf2PasswordEncoder, or
  * SCryptPasswordEncoder. Even better use {@link DelegatingPasswordEncoder} which supports
- * password upgrades.
+ * password upgrades. There are no plans to remove this support. It is deprecated to indicate
+ * that this is a legacy implementation and using it is considered insecure.
  */
 @Deprecated
 public class LdapShaPasswordEncoder implements PasswordEncoder {

crypto/src/main/java/org/springframework/security/crypto/password/Md4PasswordEncoder.java

@@ -73,7 +73,8 @@ import java.util.Base64;
  * @deprecated Digest based password encoding is not considered secure. Instead use an
  * adaptive one way funciton like BCryptPasswordEncoder, Pbkdf2PasswordEncoder, or
  * SCryptPasswordEncoder. Even better use {@link DelegatingPasswordEncoder} which supports
- * password upgrades.
+ * password upgrades. There are no plans to remove this support. It is deprecated to indicate
+ * that this is a legacy implementation and using it is considered insecure.
  */
 @Deprecated
 public class Md4PasswordEncoder implements PasswordEncoder {

crypto/src/main/java/org/springframework/security/crypto/password/MessageDigestPasswordEncoder.java

@@ -76,7 +76,8 @@ import java.util.Base64;
  * @deprecated Digest based password encoding is not considered secure. Instead use an
  * adaptive one way funciton like BCryptPasswordEncoder, Pbkdf2PasswordEncoder, or
  * SCryptPasswordEncoder. Even better use {@link DelegatingPasswordEncoder} which supports
- * password upgrades.
+ * password upgrades. There are no plans to remove this support. It is deprecated to indicate
+ * that this is a legacy implementation and using it is considered insecure.
  */
 @Deprecated
 public class MessageDigestPasswordEncoder implements PasswordEncoder {

crypto/src/main/java/org/springframework/security/crypto/password/StandardPasswordEncoder.java

@@ -41,9 +41,10 @@ import org.springframework.security.crypto.keygen.KeyGenerators;
  * @author Keith Donald
  * @author Luke Taylor
  * @deprecated Digest based password encoding is not considered secure. Instead use an
- * adaptive one way funciton like BCryptPasswordEncoder, Pbkdf2PasswordEncoder, or
+ * adaptive one way function like BCryptPasswordEncoder, Pbkdf2PasswordEncoder, or
  * SCryptPasswordEncoder. Even better use {@link DelegatingPasswordEncoder} which supports
- * password upgrades.
+ * password upgrades. There are no plans to remove this support. It is deprecated to indicate
+ * that this is a legacy implementation and using it is considered insecure.
  */
 @Deprecated
 public final class StandardPasswordEncoder implements PasswordEncoder {