Add currentThread method to KiwiEnvironment (#959)

Closes #942

src/main/java/org/kiwiproject/base/DefaultEnvironment.java

@@ -149,6 +149,11 @@ public Optional<ProcessHandle> processHandleOfPid(long pid) {
         return ProcessHandle.of(pid);
     }
 
+    @Override
+    public Thread currentThread() {
+        return Thread.currentThread();
+    }
+
     @Override
     public void sleep(long milliseconds) throws InterruptedException {
         Thread.sleep(milliseconds);

src/main/java/org/kiwiproject/base/KiwiEnvironment.java

@@ -190,6 +190,14 @@ public interface KiwiEnvironment {
      */
     ProcessHandle currentProcessHandle();
 
+    /**
+     * Returns a reference to the currently executing thread object.
+     *
+     * @return the currently executing thread
+     * @see Thread#currentThread()
+     */
+    Thread currentThread();
+
     /**
      * Tries to obtain a {@link ProcessHandle} for a process with the given ID. If the process does not exist, then
      * an empty Optional is returned.

src/test/java/org/kiwiproject/base/DefaultEnvironmentTest.java

@@ -288,6 +288,11 @@ void shouldReturnEmptyOptional_WhenProcessDoesNotExist() {
         }
     }
 
+    @Test
+    void shouldReturnCurrentThread() {
+        assertThat(env.currentThread()).isSameAs(Thread.currentThread());
+    }
+
     @Test
     void testSleep() throws InterruptedException {
         long sleepTime = 50;