Avoid jextracting +SwiftJava files

Author: ktoso

Sources/JExtractSwiftLib/Swift2Java.swift

@@ -124,8 +124,17 @@ public struct SwiftToJava {
   }
 
   func canExtract(from file: URL) -> Bool {
-    file.lastPathComponent.hasSuffix(".swift") ||
-    file.lastPathComponent.hasSuffix(".swiftinterface")
+    guard file.lastPathComponent.hasSuffix(".swift") else {
+      return false
+    }
+    guard file.lastPathComponent.hasSuffix(".swiftinterface") else { 
+      return false
+    }
+    guard !file.lastPathComponent.hasSuffix("+SwiftJava.swift") else { 
+      return false
+    }
+
+    return true
   }
 
 }