During the definition & development of Java 8, as a part of the Lambda expressions support Umbrella JSR https://bugs.openjdk.java.net/browse/JDK-7115044 ) there existed experimental support to allow interface methods being private. However this experimental feature didn't make the final cut.As part of https://bugs.openjdk.java.net/browse/JDK-8042880 targeted for Java SE 9, we would like toresurrect support for this feature.