Add example illustrating how to query credential store created from C…

…LI in the java code

existing-credential-store-query/README.md

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+Query existing credential store from code
+=============================================================
+
+This example demonstrates how to programmatically query credential store that was created with WildFly CLI.
+
+Add a credential store with aliases via WildFly CLI:
+
+```shell
+/subsystem=elytron/credential-store=my_credential_store:add(location="PATH/TO/credential-store.cs", credential-reference={clear-text=StorePassword},create=true)
+{"outcome" => "success"}
+/subsystem=elytron/credential-store=my_credential_store:add-alias(alias=my-secret-db-password, secret-value="db-secret")
+{"outcome" => "success"}
+/subsystem=elytron/credential-store=my_credential_store:add-alias(alias=my-secret-access-password, secret-value="access-pw")
+{"outcome" => "success"}
+```
+Credential Store has been created and 2 aliases `my-secret-access-password` and `my-secret-db-password` have been added.
+
+Look at `ExistingCredentialStoreQueryExample` class to see how this credential store can be queried from code. For creation and population of credential store from code, please see `credential-store` example in this repository.
+
+Run this command to execute this class:
+```shell
+    $ mvn clean install exec:exec
+```
+
+Expected output:
+```
+************************************
+Current Aliases in credential store:
+- my-secret-db-password
+- my-secret-access-password
+************************************
+Your secret key for alias my-secret-db-password is: db-secret
+```

existing-credential-store-query/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.wildfly.security.examples</groupId>
+    <artifactId>existing-credential-store-query</artifactId>
+    <version>2.0.0.Alpha1-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>1.8</maven.compiler.source>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+
+        <version.wildfly>27.0.1.Final</version.wildfly>
+    </properties>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>org.wildfly.bom</groupId>
+                <artifactId>wildfly-ee</artifactId>
+                <scope>import</scope>
+                <type>pom</type>
+                <version>${version.wildfly}</version>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.wildfly.security</groupId>
+            <artifactId>wildfly-elytron-credential-store</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.wildfly.security</groupId>
+            <artifactId>wildfly-elytron-password-impl</artifactId>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- Add the Maven exec plug-in to allow us to run a Java program via Maven -->
+            <plugin>
+                <groupId>org.codehaus.mojo</groupId>
+                <artifactId>exec-maven-plugin</artifactId>
+                <configuration>
+                    <executable>java</executable>
+                    <workingDirectory>${project.build.directory}/exec-working-directory</workingDirectory>
+                    <arguments>
+                        <!-- automatically creates the classpath using all project dependencies,
+                                      also adding the project build directory -->
+                        <argument>-classpath</argument>
+                        <classpath></classpath>
+                        <argument>org.wildfly.security.examples.ExistingCredentialStoreQueryExample</argument>
+                    </arguments>
+                </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

existing-credential-store-query/src/main/java/org/wildfly/security/examples/ExistingCredentialStoreQueryExample.java

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+/*
+ * Copyright 2023 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.wildfly.security.examples;
+
+import java.security.Provider;
+import java.security.Security;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.wildfly.security.auth.server.IdentityCredentials;
+import org.wildfly.security.credential.PasswordCredential;
+import org.wildfly.security.credential.store.CredentialStore;
+import org.wildfly.security.credential.store.CredentialStore.CredentialSourceProtectionParameter;
+import org.wildfly.security.credential.store.CredentialStore.ProtectionParameter;
+import org.wildfly.security.credential.store.WildFlyElytronCredentialStoreProvider;
+import org.wildfly.security.password.Password;
+import org.wildfly.security.password.WildFlyElytronPasswordProvider;
+import org.wildfly.security.password.interfaces.ClearPassword;
+
+/**
+ * Example demonstrating how a credential store created by WildFly CLI can be queried.
+ */
+public class ExistingCredentialStoreQueryExample {
+
+    private static final Provider CREDENTIAL_STORE_PROVIDER = new WildFlyElytronCredentialStoreProvider();
+    private static final Provider PASSWORD_PROVIDER = new WildFlyElytronPasswordProvider();
+
+    static {
+        Security.addProvider(PASSWORD_PROVIDER);
+    }
+
+    public static void main(String[] args) throws Exception {
+
+        /*
+         * Create a ProtectionParameter for access to the store.
+         */
+        Password storePassword = ClearPassword.createRaw(ClearPassword.ALGORITHM_CLEAR, "StorePassword".toCharArray());
+        ProtectionParameter protectionParameter = new CredentialSourceProtectionParameter(IdentityCredentials.NONE.withCredential(new PasswordCredential(storePassword)));
+        // Get an instance of the CredentialStore
+        CredentialStore credentialStore = CredentialStore.getInstance("KeyStoreCredentialStore", CREDENTIAL_STORE_PROVIDER);
+
+        // Initialise the CredentialStore
+        Map<String, String> configuration = new HashMap<>();
+        configuration.put("location", "/PATH/TO/credential-store.cs");
+        configuration.put("modifiable", "true");
+        configuration.put("keyStoreType", "JCEKS");
+        credentialStore.initialize(configuration, protectionParameter);
+
+        System.out.println("************************************");
+        System.out.println("Current Aliases in credential store: ");
+        for (String alias : credentialStore.getAliases()) {
+            System.out.print(" - ");
+            System.out.println(alias);
+        }
+        System.out.println("************************************");
+
+        String queriedAlias = "my-secret-db-password";
+        final PasswordCredential credential = credentialStore.retrieve(queriedAlias,PasswordCredential.class);
+        final Password password = credential.castAndApply(PasswordCredential.class, ClearPassword.ALGORITHM_CLEAR, PasswordCredential::getPassword);
+        final ClearPassword clearPassword = password.castAs(ClearPassword.class, ClearPassword.ALGORITHM_CLEAR);
+        System.out.println("Your secret key for alias " + queriedAlias + " is: " + new String(clearPassword.getPassword()));
+    }
+
+}