New: Add lightwalletd service for fetching t-addr txs.

src/main/java/cash/z/ecc/android/sdk/service/LightWalletGrpcService.kt

@@ -97,6 +97,20 @@ class LightWalletGrpcService private constructor(
         return channel.createStub().getTransaction(Service.TxFilter.newBuilder().setHash(ByteString.copyFrom(txId)).build())
     }
 
+    override fun getTAddressTransactions(
+        tAddress: String,
+        blockHeightRange: IntRange
+    ): List<Service.RawTransaction> {
+        if (blockHeightRange.isEmpty() || tAddress.isBlank()) return listOf()
+
+        channel.resetConnectBackoff()
+        val result = channel.createStub().getAddressTxids(
+            Service.TransparentAddressBlockFilter.newBuilder().setAddress(tAddress)
+                .setRange(blockHeightRange.toBlockRange()).build()
+        )
+        return result.toList()
+    }
+
     override fun reconnect() {
         twig("closing existing channel and then reconnecting to" +
                 " ${connectionInfo.host}:${connectionInfo.port}?usePlaintext=${connectionInfo.usePlaintext}")

src/main/java/cash/z/ecc/android/sdk/service/LightWalletService.kt

@@ -1,5 +1,6 @@
 package cash.z.ecc.android.sdk.service
 
+import cash.z.ecc.android.sdk.db.entity.ConfirmedTransaction
 import cash.z.wallet.sdk.rpc.CompactFormats
 import cash.z.wallet.sdk.rpc.Service
 
@@ -52,6 +53,15 @@ interface LightWalletService {
      */
     fun submitTransaction(spendTransaction: ByteArray): Service.SendResponse
 
+    /**
+     * Gets all the transactions for a given t-address over the given range.  In practice, this is
+     * effectively the same as an RPC call to a node that's running an insight server. The data is
+     * indexed and responses are fairly quick.
+     *
+     * @return a list of transactions that correspond to the given address for the given range.
+     */
+    fun getTAddressTransactions(tAddress: String, blockHeightRange: IntRange): List<Service.RawTransaction>
+
     /**
      * Fetch the details of a known transaction.
      *