Remove the copy of Guava from within the finance module. (#1362)

experimental/build.gradle

@@ -26,6 +26,8 @@ dependencies {
     // ObjectWeb Asm: a library for synthesising and working with JVM bytecode.
     compile "org.ow2.asm:asm:5.0.4"
 
+    compile "com.google.guava:guava:$guava_version"
+
     testCompile "junit:junit:$junit_version"
     testCompile project(':test-utils')
 }

finance/build.gradle

@@ -15,8 +15,6 @@ dependencies {
     // and CorDapps using :finance features should use 'cordapp' not 'compile' linkage.
     cordaCompile project(':core')
 
-    compile "com.google.guava:guava:$guava_version"
-
     testCompile project(':test-utils')
     testCompile project(path: ':core', configuration: 'testArtifacts')
     testCompile "junit:junit:$junit_version"

finance/src/main/java/net/corda/finance/contracts/JavaCommercialPaper.java

@@ -1,8 +1,6 @@
 package net.corda.finance.contracts;
 
 import co.paralleluniverse.fibers.Suspendable;
-import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Iterables;
 import kotlin.Unit;
 import net.corda.core.contracts.*;
 import net.corda.core.crypto.testing.NullPublicKey;
@@ -20,6 +18,7 @@ import org.jetbrains.annotations.Nullable;
 import java.time.Instant;
 import java.util.Collections;
 import java.util.Currency;
+import java.util.Iterator;
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -128,7 +127,7 @@ public class JavaCommercialPaper implements Contract {
         @NotNull
         @Override
         public List<AbstractParty> getParticipants() {
-            return ImmutableList.of(this.owner);
+            return Collections.singletonList(this.owner);
         }
     }
 
@@ -175,7 +174,7 @@ public class JavaCommercialPaper implements Contract {
         final List<AuthenticatedObject<CommandData>> commands = tx.getCommands().stream().filter(
                 it -> it.getValue() instanceof Commands
         ).collect(Collectors.toList());
-        final AuthenticatedObject<CommandData> command = Iterables.getOnlyElement(commands);
+        final AuthenticatedObject<CommandData> command = onlyElementOf(commands);
         final TimeWindow timeWindow = tx.getTimeWindow();
 
         for (final LedgerTransaction.InOutGroup<State, State> group : groups) {
@@ -184,7 +183,7 @@ public class JavaCommercialPaper implements Contract {
             if (command.getValue() instanceof Commands.Move) {
                 final AuthenticatedObject<Commands.Move> cmd = requireSingleCommand(tx.getCommands(), Commands.Move.class);
                 // There should be only a single input due to aggregation above
-                final State input = Iterables.getOnlyElement(inputs);
+                final State input = onlyElementOf(inputs);
 
                 if (!cmd.getSigners().contains(input.getOwner().getOwningKey()))
                     throw new IllegalStateException("Failed requirement: the transaction is signed by the owner of the CP");
@@ -197,7 +196,7 @@ public class JavaCommercialPaper implements Contract {
                 final AuthenticatedObject<Commands.Redeem> cmd = requireSingleCommand(tx.getCommands(), Commands.Redeem.class);
 
                 // There should be only a single input due to aggregation above
-                final State input = Iterables.getOnlyElement(inputs);
+                final State input = onlyElementOf(inputs);
 
                 if (!cmd.getSigners().contains(input.getOwner().getOwningKey()))
                     throw new IllegalStateException("Failed requirement: the transaction is signed by the owner of the CP");
@@ -218,7 +217,7 @@ public class JavaCommercialPaper implements Contract {
                 });
             } else if (command.getValue() instanceof Commands.Issue) {
                 final AuthenticatedObject<Commands.Issue> cmd = requireSingleCommand(tx.getCommands(), Commands.Issue.class);
-                final State output = Iterables.getOnlyElement(outputs);
+                final State output = onlyElementOf(outputs);
                 final Instant time = null == timeWindow
                         ? null
                         : timeWindow.getUntilTime();
@@ -257,4 +256,13 @@ public class JavaCommercialPaper implements Contract {
         tx.addOutputState(new TransactionState<>(new State(paper.getState().getData().getIssuance(), newOwner, paper.getState().getData().getFaceValue(), paper.getState().getData().getMaturityDate()), paper.getState().getNotary(), paper.getState().getEncumbrance()));
         tx.addCommand(new Command<>(new Commands.Move(), paper.getState().getData().getOwner().getOwningKey()));
     }
+
+    private static <T> T onlyElementOf(Iterable<T> iterable) {
+        Iterator<T> iter = iterable.iterator();
+        T item = iter.next();
+        if (iter.hasNext()) {
+            throw new IllegalArgumentException("Iterable has more than one element!");
+        }
+        return item;
+    }
 }