The following are required by the Java Packager:

java.base/sun.security.pkcs
java.base/sun.security.timestamp
java.base/sun.security.x509

Once public APIs are available replace the usage of these classes. There will need to be changes in build.gradle:

                "-XaddExports:java.base/sun.security.pkcs=ALL-UNNAMED,"
                        + "java.base/sun.security.timestamp=ALL-UNNAMED,"
                        + "java.base/sun.security.x509=ALL-UNNAMED,",

And the source files:

/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:52: error: package sun.security.pkcs does not exist
import sun.security.pkcs.ContentInfo;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:53: error: package sun.security.pkcs does not exist
import sun.security.pkcs.PKCS7;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:54: error: package sun.security.pkcs does not exist
import sun.security.pkcs.PKCS9Attribute;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:55: error: package sun.security.pkcs does not exist
import sun.security.pkcs.PKCS9Attributes;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:56: error: package sun.security.pkcs does not exist
import sun.security.pkcs.ParsingException;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:57: error: package sun.security.pkcs does not exist
import sun.security.pkcs.SignerInfo;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:58: error: package sun.security.timestamp does not exist
import sun.security.timestamp.TimestampToken;
                             ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:59: error: package sun.security.x509 does not exist
import sun.security.x509.AlgorithmId;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:60: error: package sun.security.x509 does not exist
import sun.security.x509.X500Name;
                        ^
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:91: error: cannot find symbol
    private final SignerInfo signerInfos[]; // for validation only
                  ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:97: error: cannot find symbol
    public static JarSignature load(byte[] rawSignature) throws ParsingException,
                                                                ^
  symbol: class ParsingException
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:140: error: cannot find symbol
    private JarSignature(Signature signature, SignerInfo[] infos, CodeSigner[] signers) {
                                              ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:172: error: cannot find symbol
    private static Signature getSignature(SignerInfo info)
                                          ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:186: error: cannot find symbol
    AlgorithmId getDigestAlgorithm() throws NoSuchAlgorithmException {
    ^
  symbol: class AlgorithmId
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:191: error: cannot find symbol
    AlgorithmId getKeyAlgorithm() throws NoSuchAlgorithmException {
    ^
  symbol: class AlgorithmId
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:339: error: cannot find symbol
    private static CodeSigner[] extractCodeSigners(SignerInfo infos[], PKCS7 block)
                                                   ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:339: error: cannot find symbol
    private static CodeSigner[] extractCodeSigners(SignerInfo infos[], PKCS7 block)
                                                                       ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:383: error: cannot find symbol
    private static Timestamp getTimestamp(SignerInfo info,
                                          ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:101: error: cannot find symbol
        PKCS7 pkcs7 = new PKCS7(rawSignature);
        ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:101: error: cannot find symbol
        PKCS7 pkcs7 = new PKCS7(rawSignature);
                          ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:102: error: cannot find symbol
        SignerInfo[] infos = pkcs7.getSignerInfos();
        ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:128: error: reference to getSignature is ambiguous
        Signature signature = getSignature(privateKey.getAlgorithm());
                              ^
  both method getSignature(String) in JarSignature and method getSignature(SignerInfo) in JarSignature match
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:188: error: cannot find symbol
        return AlgorithmId.get(name);
               ^
  symbol: variable AlgorithmId
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:193: error: cannot find symbol
        return AlgorithmId.get(name);
               ^
  symbol: variable AlgorithmId
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:244: error: cannot find symbol
        AlgorithmId digestAlgId = getDigestAlgorithm();
        ^
  symbol: class AlgorithmId
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:245: error: cannot find symbol
        AlgorithmId[] digestAlgIds = {digestAlgId};
        ^
  symbol: class AlgorithmId
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:246: error: cannot find symbol
        ContentInfo contentInfo = new ContentInfo(ContentInfo.DATA_OID, null);
        ^
  symbol: class ContentInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:246: error: cannot find symbol
        ContentInfo contentInfo = new ContentInfo(ContentInfo.DATA_OID, null);
                                      ^
  symbol: class ContentInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:246: error: cannot find symbol
        ContentInfo contentInfo = new ContentInfo(ContentInfo.DATA_OID, null);
                                                  ^
  symbol: variable ContentInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:250: error: cannot find symbol
        SignerInfo signerInfo =
        ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:251: error: cannot find symbol
                new SignerInfo((X500Name) issuerName, serialNumber, digestAlgId,
                    ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:251: error: cannot find symbol
                new SignerInfo((X500Name) issuerName, serialNumber, digestAlgId,
                                ^
  symbol: class X500Name
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:254: error: cannot find symbol
        SignerInfo[] signerInfos = {signerInfo};
        ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:255: error: cannot find symbol
        PKCS7 pkcs7 = new PKCS7(digestAlgIds, contentInfo, certChain,
        ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:255: error: cannot find symbol
        PKCS7 pkcs7 = new PKCS7(digestAlgIds, contentInfo, certChain,
                          ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:347: error: cannot find symbol
            SignerInfo info = infos[i];
            ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:390: error: cannot find symbol
        PKCS9Attributes unsignedAttrs = info.getUnauthenticatedAttributes();
        ^
  symbol: class PKCS9Attributes
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:392: error: cannot find symbol
            PKCS9Attribute timestampTokenAttr =
            ^
  symbol: class PKCS9Attribute
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:395: error: cannot find symbol
                PKCS7 timestampToken =
                ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:396: error: cannot find symbol
                        new PKCS7((byte[]) timestampTokenAttr.getValue());
                            ^
  symbol: class PKCS7
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:402: error: cannot find symbol
                SignerInfo[] tsa =
                ^
  symbol: class SignerInfo
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:409: error: cannot find symbol
                TimestampToken timestampTokenInfo =
                ^
  symbol: class TimestampToken
  location: class JarSignature
/Users/cbensen/source/pull/fx9packager/fx9sandbox/rt/modules/fxpackager/src/main/java/com/sun/javafx/tools/packager/JarSignature.java:410: error: cannot find symbol
                        new TimestampToken(encodedTimestampTokenInfo);