Stop exposing registry write access

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

@@ -319,4 +319,7 @@ default Descriptor describe() {
         descriptor.add(providers().describe());
         return descriptor;
     }
+
+    /** Registers an IO instance, bypassing create method. Used in testing */
+    void register(IO instance);
 }

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

@@ -37,9 +37,7 @@
 import com.pi4j.provider.Providers;
 import com.pi4j.provider.impl.DefaultProviders;
 import com.pi4j.registry.Registry;
-import com.pi4j.registry.impl.DefaultRegistry;
 import com.pi4j.runtime.Runtime;
-import com.pi4j.runtime.impl.DefaultRuntime;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -58,7 +56,6 @@ public class DefaultContext implements Context {
     private Runtime runtime = null;
     private ContextConfig config = null;
     private Providers providers = null;
-    private Registry registry = null;
     private BoardInfo boardInfo = null;
 
     /**
@@ -87,10 +84,7 @@ protected DefaultContext(ContextConfig config) {
         this.config = config;
 
         // create internal runtime state instance  (READ-ONLY ACCESS OBJECT)
-        this.runtime = DefaultRuntime.newInstance(this);
-
-        // create API accessible registry instance  (READ-ONLY ACCESS OBJECT)
-        this.registry = DefaultRegistry.newInstance(this.runtime.registry());
+        this.runtime = Runtime.newInstance(this);
 
         // create API accessible providers instance  (READ-ONLY ACCESS OBJECT)
         this.providers = DefaultProviders.newInstance(this.runtime.providers());
@@ -117,7 +111,7 @@ protected DefaultContext(ContextConfig config) {
 
     /** {@inheritDoc} */
     @Override
-    public Registry registry() { return this.registry; }
+    public Registry registry() { return this.runtime.registry(); }
 
     /** {@inheritDoc} */
     @Override
@@ -139,11 +133,11 @@ public Context shutdown() throws ShutdownException {
 
 	@Override
 	public <T extends IO> void shutdown(T instance) {
-		runtime.registry().remove(instance);
+		runtime.shutdown(instance);
 	}
 	@Override
 	public <T extends IO> T shutdown(String id) {
-		return runtime.registry().remove(id);
+		return runtime.shutdown(runtime.registry().get(id));
 	}
 
     @Override
@@ -191,4 +185,9 @@ public Context removeListener(InitializedListener... listener) {
         this.runtime.removeListener(listener);
         return this;
     }
+
+    @Override
+    public void register(IO instance) {
+        runtime.register(instance);
+    }
 }

pi4j-core/src/main/java/com/pi4j/io/i2c/I2CBase.java

@@ -70,7 +70,10 @@ public boolean isOpen() {
      */
     @Override
     public void close() {
-        this.isOpen = false;
+        if (isOpen) {
+            this.isOpen = false;
+            context().shutdown(this);
+        }
     }
 
     /**

pi4j-core/src/main/java/com/pi4j/registry/Registry.java

@@ -29,10 +29,8 @@
 import com.pi4j.common.Descriptor;
 import com.pi4j.io.IO;
 import com.pi4j.io.IOType;
-import com.pi4j.io.exception.IOAlreadyExistsException;
 import com.pi4j.io.exception.IOInvalidIDException;
 import com.pi4j.io.exception.IONotFoundException;
-import com.pi4j.io.exception.IOShutdownException;
 import com.pi4j.provider.Provider;
 
 import java.util.Collections;
@@ -41,7 +39,7 @@
 import java.util.stream.Collectors;
 
 /**
- * <p>Registry interface.</p>
+ * An immutable view of the registry that holds all registered I/O instances.
  *
  * @author Robert Savage (<a href="http://www.savagehomeautomation.com">http://www.savagehomeautomation.com</a>)
  * @version $Id: $Id
@@ -169,28 +167,6 @@ default <P extends Provider, T extends IO> Map<String, T> allByProvider(String p
         return Collections.unmodifiableMap(result);
     }
 
-    /**
-     * <p>add.</p>
-     *
-     * @param instance a {@link com.pi4j.io.IO} object.
-     * @return this
-     * @throws com.pi4j.io.exception.IOAlreadyExistsException if any.
-     * @throws com.pi4j.io.exception.IOInvalidIDException     if any.
-     */
-    Registry add(IO instance) throws IOAlreadyExistsException, IOInvalidIDException;
-
-    /**
-     * <p>remove.</p>
-     *
-     * @param id  a {@link java.lang.String} object.
-     * @param <T> a T object.
-     * @return a T object.
-     * @throws com.pi4j.io.exception.IONotFoundException  if any.
-     * @throws com.pi4j.io.exception.IOInvalidIDException if any.
-     * @throws com.pi4j.io.exception.IOShutdownException  if any.
-     */
-    <T extends IO> T remove(String id) throws IONotFoundException, IOInvalidIDException, IOShutdownException;
-
     /**
      * <p>describe.</p>
      *