Remove comments about sequence numbers being disabled.

As of Bitcoin Core 0.12, sequence numbers are used for the infamous opt-in full replace-by-fee feature.

core/src/main/java/org/bitcoinj/core/TransactionInput.java

@@ -46,9 +46,7 @@ public class TransactionInput extends ChildMessage {
     // Magic outpoint index that indicates the input is in fact unconnected.
     private static final long UNCONNECTED = 0xFFFFFFFFL;
 
-    // Allows for altering transactions after they were broadcast. Tx replacement is currently disabled in the C++
-    // client so this is always the UINT_MAX.
-    // TODO: Document this in more detail and build features that use it.
+    // Allows for altering transactions after they were broadcast.
     private long sequence;
     // Data needed to connect to the output of the transaction we're gathering coins from.
     private TransactionOutPoint outpoint;
@@ -193,8 +191,7 @@ public class TransactionInput extends ChildMessage {
      * Sequence numbers allow participants in a multi-party transaction signing protocol to create new versions of the
      * transaction independently of each other. Newer versions of a transaction can replace an existing version that's
      * in nodes memory pools if the existing version is time locked. See the Contracts page on the Bitcoin wiki for
-     * examples of how you can use this feature to build contract protocols. Note that as of 2012 the tx replacement
-     * feature is disabled so sequence numbers are unusable.
+     * examples of how you can use this feature to build contract protocols.
      */
     public long getSequenceNumber() {
         return sequence;
@@ -204,8 +201,7 @@ public class TransactionInput extends ChildMessage {
      * Sequence numbers allow participants in a multi-party transaction signing protocol to create new versions of the
      * transaction independently of each other. Newer versions of a transaction can replace an existing version that's
      * in nodes memory pools if the existing version is time locked. See the Contracts page on the Bitcoin wiki for
-     * examples of how you can use this feature to build contract protocols. Note that as of 2012 the tx replacement
-     * feature is disabled so sequence numbers are unusable.
+     * examples of how you can use this feature to build contract protocols.
      */
     public void setSequenceNumber(long sequence) {
         unCache();

core/src/main/java/org/bitcoinj/wallet/Protos.java

@@ -4879,7 +4879,7 @@ public final class Protos {
      * <code>optional uint32 sequence = 4;</code>
      *
      * <pre>
-     * Sequence number. Currently unused, but intended for contracts in future.
+     * Sequence number.
      * </pre>
      */
     boolean hasSequence();
@@ -4887,7 +4887,7 @@ public final class Protos {
      * <code>optional uint32 sequence = 4;</code>
      *
      * <pre>
-     * Sequence number. Currently unused, but intended for contracts in future.
+     * Sequence number.
      * </pre>
      */
     int getSequence();
@@ -5101,7 +5101,7 @@ public final class Protos {
      * <code>optional uint32 sequence = 4;</code>
      *
      * <pre>
-     * Sequence number. Currently unused, but intended for contracts in future.
+     * Sequence number.
      * </pre>
      */
     public boolean hasSequence() {
@@ -5111,7 +5111,7 @@ public final class Protos {
      * <code>optional uint32 sequence = 4;</code>
      *
      * <pre>
-     * Sequence number. Currently unused, but intended for contracts in future.
+     * Sequence number.
      * </pre>
      */
     public int getSequence() {
@@ -5617,7 +5617,7 @@ public final class Protos {
        * <code>optional uint32 sequence = 4;</code>
        *
        * <pre>
-       * Sequence number. Currently unused, but intended for contracts in future.
+       * Sequence number.
        * </pre>
        */
       public boolean hasSequence() {
@@ -5627,7 +5627,7 @@ public final class Protos {
        * <code>optional uint32 sequence = 4;</code>
        *
        * <pre>
-       * Sequence number. Currently unused, but intended for contracts in future.
+       * Sequence number.
        * </pre>
        */
       public int getSequence() {
@@ -5637,7 +5637,7 @@ public final class Protos {
        * <code>optional uint32 sequence = 4;</code>
        *
        * <pre>
-       * Sequence number. Currently unused, but intended for contracts in future.
+       * Sequence number.
        * </pre>
        */
       public Builder setSequence(int value) {
@@ -5650,7 +5650,7 @@ public final class Protos {
        * <code>optional uint32 sequence = 4;</code>
        *
        * <pre>
-       * Sequence number. Currently unused, but intended for contracts in future.
+       * Sequence number.
        * </pre>
        */
       public Builder clearSequence() {

core/src/wallet.proto

@@ -149,7 +149,7 @@ message TransactionInput {
   required uint32 transaction_out_point_index = 2;
   // Script that contains the signatures/pubkeys.
   required bytes script_bytes = 3;
-  // Sequence number. Currently unused, but intended for contracts in future.
+  // Sequence number.
   optional uint32 sequence = 4;
   // Value of connected output, if known
   optional int64 value = 5;