When trying to compile Spigot with the most recent BuildTools on Windows I get the following error. On my Linux Box it works fine.

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Test set: org.bukkit.craftbukkit.inventory.ItemFactoryTest
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Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.265 sec <<< FAILURE! - in org.bukkit.craftbukkit.inventory.ItemFactoryTest
testKnownAttributes(org.bukkit.craftbukkit.inventory.ItemFactoryTest) Time elapsed: 0.265 sec <<< ERROR!
java.lang.UnsatisfiedLinkError: Can't obtain static newInstance method for class com.sun.jna.Structure
at com.sun.jna.Native.initIDs(Native Method)
at com.sun.jna.Native.<clinit>(Native.java:135)
at com.sun.jna.Pointer.<clinit>(Pointer.java:42)
at com.sun.jna.platform.win32.WinReg$HKEY.<init>(WinReg.java:32)
at com.sun.jna.platform.win32.WinReg.<clinit>(WinReg.java:61)
at oshi.software.os.windows.WindowsHardwareAbstractionLayer.getProcessors(WindowsHardwareAbstractionLayer.java:33)
at net.minecraft.server.SystemUtils.<clinit>(SourceFile:16)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at org.bukkit.craftbukkit.inventory.ItemFactoryTest.testKnownAttributes(ItemFactoryTest.java:31)