throw UnsupportedOperationException instead of returning false

usbSerialForAndroid/build.gradle

@@ -15,6 +15,10 @@ android {
                 'rfc2217_server_nonstandard_baudrates': 'true',   // true    false     false
         ]
     }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
 }
 
 dependencies {