Created an API to get encoded message of SubmitPuds

    method @RequiresPermission(android.Manifest.permission.MODIFY_PHONE_STATE) public void sendMultipartTextMessageWithoutPersisting(String, String, java.util.List<java.lang.String>, java.util.List<android.app.PendingIntent>, java.util.List<android.app.PendingIntent>);

  }

  public class SmsMessage {

    method @NonNull @RequiresPermission(android.Manifest.permission.BLUETOOTH_PRIVILEGED) public static byte[] getSubmitPduEncodedMessage(boolean, @NonNull String, @NonNull String, int, int, int, int, int, int);

  }

  public class SubscriptionInfo implements android.os.Parcelable {

    method public boolean areUiccApplicationsEnabled();

    method @Nullable public java.util.List<android.telephony.UiccAccessRule> getAccessRules();

import static android.telephony.TelephonyManager.PHONE_TYPE_CDMA;

import android.Manifest;

import android.annotation.IntDef;

import android.annotation.NonNull;

import android.annotation.Nullable;

import android.annotation.RequiresPermission;

import android.annotation.StringDef;

import android.annotation.SystemApi;

import android.compat.annotation.UnsupportedAppUsage;

import android.content.res.Resources;

import android.os.Binder;

import com.android.internal.telephony.GsmAlphabet.TextEncodingDetails;

import com.android.internal.telephony.Sms7BitEncodingTranslator;

import com.android.internal.telephony.SmsConstants;

import com.android.internal.telephony.SmsHeader;

import com.android.internal.telephony.SmsMessageBase;

import com.android.internal.telephony.SmsMessageBase.SubmitPduBase;

import com.android.internal.telephony.cdma.sms.UserData;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

        UNKNOWN, CLASS_0, CLASS_1, CLASS_2, CLASS_3;

    }

    /** @hide */

    @IntDef(prefix = { "ENCODING_" }, value = {

            ENCODING_UNKNOWN,

            ENCODING_7BIT,

            ENCODING_8BIT,

            ENCODING_16BIT

    })

    @Retention(RetentionPolicy.SOURCE)

    public @interface EncodingSize {}

    /** User data text encoding code unit size */

    public static final int ENCODING_UNKNOWN = 0;

    public static final int ENCODING_7BIT = 1;

        return new SubmitPdu(spb);

    }

    /**

     * Get an SMS-SUBMIT PDU's encoded message.

     * This is used by Bluetooth MAP profile to handle long non UTF-8 SMS messages.

     *

     * @param isTypeGsm true when message's type is GSM, false when type is CDMA

     * @param destinationAddress the address of the destination for the message

     * @param message message content

     * @param encoding User data text encoding code unit size

     * @param languageTable GSM national language table to use, specified by 3GPP

     *                      23.040 9.2.3.24.16

     * @param languageShiftTable GSM national language shift table to use, specified by 3GPP

     *                           23.040 9.2.3.24.15

     * @param refNumber parameter to create SmsHeader

     * @param seqNumber parameter to create SmsHeader

     * @param msgCount parameter to create SmsHeader

     * @return a byte[] containing the encoded message

     *

     * @hide

     */

    @RequiresPermission(Manifest.permission.BLUETOOTH_PRIVILEGED)

    @SystemApi

    @NonNull

    public static byte[] getSubmitPduEncodedMessage(boolean isTypeGsm,

                                                    @NonNull String destinationAddress,

                                                    @NonNull String message,

                                                    @EncodingSize int encoding, int languageTable,

                                                    int languageShiftTable, int refNumber,

                                                    int seqNumber, int msgCount) {

        byte[] data;

        SmsHeader.ConcatRef concatRef = new SmsHeader.ConcatRef();

        concatRef.refNumber = refNumber;

        concatRef.seqNumber = seqNumber;  // 1-based sequence

        concatRef.msgCount = msgCount;

        // We currently set this to true since our messaging app will never

        // send more than 255 parts (it converts the message to MMS well before that).

        // However, we should support 3rd party messaging apps that might need 16-bit

        // references

        // Note:  It's not sufficient to just flip this bit to true; it will have

        // ripple effects (several calculations assume 8-bit ref).

        concatRef.isEightBits = true;

        SmsHeader smsHeader = new SmsHeader();

        smsHeader.concatRef = concatRef;

        /* Depending on the type, call either GSM or CDMA getSubmitPdu(). The encoding

         * will be determined(again) by getSubmitPdu().

         * All packets need to be encoded using the same encoding, as the bMessage

         * only have one filed to describe the encoding for all messages in a concatenated

         * SMS... */

        if (encoding == ENCODING_7BIT) {

            smsHeader.languageTable = languageTable;

            smsHeader.languageShiftTable = languageShiftTable;

        }

        if (isTypeGsm) {

            data = com.android.internal.telephony.gsm.SmsMessage.getSubmitPdu(null,

                destinationAddress, message, false,

                SmsHeader.toByteArray(smsHeader), encoding, languageTable,

                languageShiftTable).encodedMessage;

        } else { // SMS_TYPE_CDMA

            UserData uData = new UserData();

            uData.payloadStr = message;

            uData.userDataHeader = smsHeader;

            if (encoding == ENCODING_7BIT) {

                uData.msgEncoding = UserData.ENCODING_GSM_7BIT_ALPHABET;

            } else { // assume UTF-16

                uData.msgEncoding = UserData.ENCODING_UNICODE_16;

            }

            uData.msgEncodingSet = true;

            data = com.android.internal.telephony.cdma.SmsMessage.getSubmitPdu(

                destinationAddress, uData, false).encodedMessage;

        }

        if (data == null) {

            return new byte[0];

        }

        return data;

    }

    /**

     * Returns the address of the SMS service center that relayed this message

     * or null if there is none.