Add password storage Kotlin samples to docs

Issue gh-8172

Author: eleftherias

docs/manual/src/docs/asciidoc/_includes/about/authentication/password-storage.adoc

@@ -68,18 +68,26 @@ You can easily construct an instance of `DelegatingPasswordEncoder`  using `Pass
 
 .Create Default DelegatingPasswordEncoder
 ====
-[source,java]
+.Java
+[source,java,role="primary"]
 ----
 PasswordEncoder passwordEncoder =
     PasswordEncoderFactories.createDelegatingPasswordEncoder();
 ----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+val passwordEncoder: PasswordEncoder = PasswordEncoderFactories.createDelegatingPasswordEncoder()
+----
 ====
 
 Alternatively, you may create your own custom instance. For example:
 
 .Create Custom DelegatingPasswordEncoder
 ====
-[source,java]
+.Java
+[source,java,role="primary"]
 ----
 String idForEncode = "bcrypt";
 Map encoders = new HashMap<>();
@@ -92,6 +100,20 @@ encoders.put("sha256", new StandardPasswordEncoder());
 PasswordEncoder passwordEncoder =
     new DelegatingPasswordEncoder(idForEncode, encoders);
 ----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+val idForEncode = "bcrypt"
+val encoders: MutableMap<String, PasswordEncoder> = mutableMapOf()
+encoders[idForEncode] = BCryptPasswordEncoder()
+encoders["noop"] = NoOpPasswordEncoder.getInstance()
+encoders["pbkdf2"] = Pbkdf2PasswordEncoder()
+encoders["scrypt"] = SCryptPasswordEncoder()
+encoders["sha256"] = StandardPasswordEncoder()
+
+val passwordEncoder: PasswordEncoder = DelegatingPasswordEncoder(idForEncode, encoders)
+----
 ====
 
 [[authentication-password-storage-dpe-format]]
@@ -180,7 +202,8 @@ There are convenience mechanisms to make this easier, but this is still not inte
 
 .withDefaultPasswordEncoder Example
 ====
-[source,java,attrs="-attributes"]
+.Java
+[source,java,role="primary",attrs="-attributes"]
 ----
 User user = User.withDefaultPasswordEncoder()
   .username("user")
@@ -190,13 +213,26 @@ User user = User.withDefaultPasswordEncoder()
 System.out.println(user.getPassword());
 // {bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG
 ----
+
+.Kotlin
+[source,kotlin,role="secondary",attrs="-attributes"]
+----
+val user = User.withDefaultPasswordEncoder()
+    .username("user")
+    .password("password")
+    .roles("user")
+    .build()
+println(user.password)
+// {bcrypt}$2a$10$dXJ3SW6G7P50lGmMkkmwe.20cQQubK3.HZWzG3YB1tlRy.fqvM/BG
+----
 ====
 
 If you are creating multiple users, you can also reuse the builder.
 
 .withDefaultPasswordEncoder Reusing the Builder
 ====
-[source,java]
+.Java
+[source,java,role="primary"]
 ----
 UserBuilder users = User.withDefaultPasswordEncoder();
 User user = users
@@ -210,6 +246,22 @@ User admin = users
   .roles("USER","ADMIN")
   .build();
 ----
+
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+val users = User.withDefaultPasswordEncoder()
+val user = users
+    .username("user")
+    .password("password")
+    .roles("USER")
+    .build()
+val admin = users
+    .username("admin")
+    .password("password")
+    .roles("USER", "ADMIN")
+    .build()
+----
 ====
 
 This does hash the password that is stored, but the passwords are still exposed in memory and in the compiled source code.
@@ -273,14 +325,27 @@ The `BCryptPasswordEncoder` implementation uses the widely supported https://en.
 In order to make it more resistent to password cracking, bcrypt is deliberately slow.
 Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.
 
-[source,java]
+.BCryptPasswordEncoder
+====
+.Java
+[source,java,role="primary"]
 ----
 // Create an encoder with strength 16
 BCryptPasswordEncoder encoder = new BCryptPasswordEncoder(16);
 String result = encoder.encode("myPassword");
 assertTrue(encoder.matches("myPassword", result));
 ----
 
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+// Create an encoder with strength 16
+val encoder = BCryptPasswordEncoder(16)
+val result: String = encoder.encode("myPassword")
+assertTrue(encoder.matches("myPassword", result))
+----
+====
+
 [[authentication-password-storage-argon2]]
 == Argon2PasswordEncoder
 
@@ -290,14 +355,27 @@ In order to defeat password cracking on custom hardware, Argon2 is a deliberatel
 Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.
 The current implementation if the `Argon2PasswordEncoder` requires BouncyCastle.
 
-[source,java]
+.Argon2PasswordEncoder
+====
+.Java
+[source,java,role="primary"]
 ----
 // Create an encoder with all the defaults
 Argon2PasswordEncoder encoder = new Argon2PasswordEncoder();
 String result = encoder.encode("myPassword");
 assertTrue(encoder.matches("myPassword", result));
 ----
 
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+// Create an encoder with all the defaults
+val encoder = Argon2PasswordEncoder()
+val result: String = encoder.encode("myPassword")
+assertTrue(encoder.matches("myPassword", result))
+----
+====
+
 [[authentication-password-storage-pbkdf2]]
 == Pbkdf2PasswordEncoder
 
@@ -306,29 +384,55 @@ In order to defeat password cracking PBKDF2 is a deliberately slow algorithm.
 Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.
 This algorithm is a good choice when FIPS certification is required.
 
-[source,java]
+.Pbkdf2PasswordEncoder
+====
+.Java
+[source,java,role="primary"]
 ----
 // Create an encoder with all the defaults
 Pbkdf2PasswordEncoder encoder = new Pbkdf2PasswordEncoder();
 String result = encoder.encode("myPassword");
 assertTrue(encoder.matches("myPassword", result));
 ----
 
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+// Create an encoder with all the defaults
+val encoder = Pbkdf2PasswordEncoder()
+val result: String = encoder.encode("myPassword")
+assertTrue(encoder.matches("myPassword", result))
+----
+====
+
 [[authentication-password-storage-scrypt]]
 == SCryptPasswordEncoder
 
 The `SCryptPasswordEncoder` implementation uses https://en.wikipedia.org/wiki/Scrypt[scrypt] algorithm to hash the passwords.
 In order to defeat password cracking on custom hardware scrypt is a deliberately slow algorithm that requires large amounts of memory.
 Like other adaptive one-way functions, it should be tuned to take about 1 second to verify a password on your system.
 
-[source,java]
+.SCryptPasswordEncoder
+====
+.Java
+[source,java,role="primary"]
 ----
 // Create an encoder with all the defaults
 SCryptPasswordEncoder encoder = new SCryptPasswordEncoder();
 String result = encoder.encode("myPassword");
 assertTrue(encoder.matches("myPassword", result));
 ----
 
+.Kotlin
+[source,kotlin,role="secondary"]
+----
+// Create an encoder with all the defaults
+val encoder = SCryptPasswordEncoder()
+val result: String = encoder.encode("myPassword")
+assertTrue(encoder.matches("myPassword", result))
+----
+====
+
 [[authentication-password-storage-other]]
 == Other PasswordEncoders