The new code from JDK-8353786 fails with the following stack on platforms with empty CPU feature String:
Caused by: java.lang.ExceptionInInitializerError: Exception java.lang.AssertionError: Invalid CPU feature name: '' [in thread "MainThread"]
at jdk.incubator.vector/jdk.incubator.vector.CPUFeatures.validateFeatures(CPUFeatures.java:53)
at jdk.incubator.vector/jdk.incubator.vector.CPUFeatures.getCPUFeatures(CPUFeatures.java:47)
at jdk.incubator.vector/jdk.incubator.vector.CPUFeatures.<clinit>(CPUFeatures.java:40)
at jdk.incubator.vector/jdk.incubator.vector.VectorMathLibrary.<clinit>(VectorMathLibrary.java:84)
at jdk.incubator.vector/jdk.incubator.vector.DoubleVector.unaryMathOp(DoubleVector.java:723)
at jdk.incubator.vector/jdk.incubator.vector.DoubleVector.lanewiseTemplate(DoubleVector.java:682)
at jdk.incubator.vector/jdk.incubator.vector.Double128Vector.lanewise(Double128Vector.java:264)
at jdk.incubator.vector/jdk.incubator.vector.Double128Vector.lanewise(Double128Vector.java:41)
at Double128VectorTests.ACOSDouble128VectorTests(Double128VectorTests.java:4052)

Observed in many jdk/incubator/vector tests.

Reason is that String[] features (CPUFeatures.java:45) contains 1 empty String instead of an array of size 0 when featuresString is an empty String.