deferred value: Memoize value to ensure at-most-once supplier call

Since we are using deferred values to defer expensive operations, we
don't want concurrent threads all performing the expensive operation.
So we memoize the result of the operation to ensure at-most-once.

Signed-off-by: BJ Hargrave <bj@hargrave.dev>

biz.aQute.bndlib/src/aQute/bnd/osgi/resource/DeferredValue.java

@@ -4,25 +4,22 @@
 
 import java.util.function.Supplier;
 
+import aQute.bnd.memoize.Memoize;
+
 class DeferredValue<T> implements Supplier<T> {
 	private final Class<T>				type;
 	private final Supplier<? extends T>	supplier;
 	private final int					hashCode;
-	private T							value;
 
 	DeferredValue(Class<T> type, Supplier<? extends T> supplier, int hashCode) {
 		this.type = requireNonNull(type);
-		this.supplier = requireNonNull(supplier);
+		this.supplier = Memoize.supplier(supplier);
 		this.hashCode = hashCode;
 	}
 
 	@Override
 	public T get() {
-		T v = value;
-		if (v == null) {
-			return value = supplier.get();
-		}
-		return v;
+		return supplier.get();
 	}
 
 	Class<T> type() {