how to invoke constructor of inner class using reflection

Following is my class:

//outer class public final class EMSToCompMessages { private EMSToCompMessages() {} //inner class public static final class CompTypeConfig extends { private CompTypeConfig(com.google.protobuf.GeneratedMessage.Builder builder) { super(builder); this.unknownFields = builder.getUnknownFields(); } private CompTypeConfig(boolean noInit) { this.unknownFields = com.google.protobuf.UnknownFieldSet.getDefaultInstance(); }

            private static final CompTypeConfig defaultInstance;
            public static CompTypeConfig getDefaultInstance() {
              return defaultInstance;
            }

            }
        }