Add missing Java throws clause for interfaces when using the %interface family of macros.

Fixes #1156.

Examples/test-suite/java/java_throws_runme.java

@@ -93,6 +93,28 @@ public class java_throws_runme {
       if (!pass)
         throw new RuntimeException("Test 6 failed");
 
+      // Interface function
+      pass = false;
+      try {
+        InterfaceTestImpl iti = new InterfaceTestImpl();
+        iti.imethod(true);
+      }
+      catch (MyException e) { pass = true; }
+
+      if (!pass)
+        throw new RuntimeException("Test interface 1 failed");
+
+      pass = false;
+      try {
+        InterfaceTestImpl iti = new InterfaceTestImpl();
+        iti.imethod(false);
+        pass = true;
+      }
+      catch (MyException e) { pass = false; }
+
+      if (!pass)
+        throw new RuntimeException("Test interface 2 failed");
+
       // Global function
       pass = false;
       try {

Examples/test-suite/java_throws.i

@@ -135,6 +135,23 @@ JAVAEXCEPTION(FeatureTest::staticMethod)
     };
 %}
 
+%include <swiginterface.i>
+%interface_impl(InterfaceTest);
+JAVAEXCEPTION(imethod)
+
+%inline %{
+    struct InterfaceTest {
+        virtual void imethod(bool raise) = 0;
+    };
+
+    struct InterfaceTestImpl : InterfaceTest {
+        void imethod(bool raise) {
+            if (raise)
+                throw MyException("raise message");
+        }
+    };
+%}
+
 // Mixing except feature and typemaps when both generate a class for the throws clause
 %typemap(in, throws="ClassNotFoundException") int both { 
     $1 = (int)$input;