allowing configuring shutdown hook

pi4j-core/src/main/java/com/pi4j/context/ContextBuilder.java

@@ -147,6 +147,34 @@ default ContextBuilder setAutoInject(boolean autoInject){
             return noAutoInject();
     }
 
+    /**
+     * <p>enableShutdownHook.</p>
+     *
+     * @return a {@link com.pi4j.context.ContextBuilder} object.
+     */
+    ContextBuilder enableShutdownHook();
+
+    /**
+     * <p>disableShutdownHook.</p>
+     *
+     * @return a {@link com.pi4j.context.ContextBuilder} object.
+     */
+    ContextBuilder disableShutdownHook();
+
+    /**
+     * <p>setShutdownHook.</p>
+     *
+     * @param enableShutdownHook a boolean.
+     *
+     * @return a {@link com.pi4j.context.ContextBuilder} object.
+     */
+    default ContextBuilder setShutdownHook(boolean enableShutdownHook) {
+        if (enableShutdownHook)
+            return enableShutdownHook();
+        else
+            return disableShutdownHook();
+    }
+
     /**
      * <p>toConfig.</p>
      *

pi4j-core/src/main/java/com/pi4j/context/ContextConfig.java

@@ -86,6 +86,12 @@ default Collection<Platform> getPlatforms(){
      * @return a boolean.
      */
     boolean autoInject();
+    /**
+     * <p>enableShutdownHook.</p>
+     *
+     * @return a boolean.
+     */
+    boolean enableShutdownHook();
     /**
      * <p>getAutoInject.</p>
      *

pi4j-core/src/main/java/com/pi4j/context/impl/DefaultContextBuilder.java

@@ -54,6 +54,7 @@ public class DefaultContextBuilder implements ContextBuilder {
     protected boolean autoDetectPlatforms = false;
     protected boolean autoDetectProviders = false;
     protected boolean autoInject = false;
+    protected boolean enableShutdownHook = true;
 
     // default platform identifier
     protected String defaultPlatformId = null;
@@ -157,6 +158,20 @@ public ContextBuilder noAutoInject() {
         return this;
     }
 
+    /** {@inheritDoc} */
+    @Override
+    public ContextBuilder enableShutdownHook() {
+        this.enableShutdownHook = true;
+        return this;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public ContextBuilder disableShutdownHook() {
+        this.enableShutdownHook = false;
+        return this;
+    }
+
     /** {@inheritDoc} */
     @Override
     public ContextBuilder property(String key, String value){
@@ -258,11 +273,17 @@ public String defaultPlatform() {
             public boolean autoDetectMockPlugins() {
                 return builder.autoDetectMockPlugins;
             }
+
             @Override
             public boolean autoDetectPlatforms() {
                 return builder.autoDetectPlatforms;
             }
 
+            @Override
+            public boolean enableShutdownHook() {
+                return builder.enableShutdownHook;
+            }
+
             @Override
             public boolean autoInject() { return builder.autoInject; }
 

pi4j-core/src/main/java/com/pi4j/runtime/impl/DefaultRuntime.java

@@ -110,15 +110,17 @@ private DefaultRuntime(Context context) {
 
         // listen for shutdown to properly clean up
         // TODO :: ADD PI4J INTERNAL SHUTDOWN CALLBACKS/EVENTS
-        java.lang.Runtime.getRuntime().addShutdownHook(new Thread(() -> {
-            try {
-                // shutdown Pi4J
-                if (!isShutdown)
-                    shutdown();
-            } catch (Exception e) {
-                logger.error("Failed to shutdown Pi4J runtime", e);
-            }
-        }, "pi4j-shutdown"));
+        if (this.context.config().enableShutdownHook()) {
+            java.lang.Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+                try {
+                    // shutdown Pi4J
+                    if (!isShutdown)
+                        shutdown();
+                } catch (Exception e) {
+                    logger.error("Failed to shutdown Pi4J runtime", e);
+                }
+            }, "pi4j-shutdown"));
+        }
     }
 
     /**