Import FoundationEssentials if available (#815)

Co-authored-by: Konrad Malawski <ktoso@apple.com>

Author: tkrajacic

Sources/JavaStdlib/JavaNet/JavaURL+Extensions.swift

@@ -12,10 +12,15 @@
 //
 //===----------------------------------------------------------------------===//
 
-import Foundation
 import SwiftJava
 import SwiftJavaJNICore
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
+import Foundation
+#endif
+
 extension JavaURL {
   @JavaMethod
   public func toURI() throws -> URI!