diff --git a/google-cloud-spanner-executor/src/main/java/com/google/cloud/executor/spanner/CloudExecutorImpl.java b/google-cloud-spanner-executor/src/main/java/com/google/cloud/executor/spanner/CloudExecutorImpl.java
index f3de36ac7b4..cbe6301974a 100644
--- a/google-cloud-spanner-executor/src/main/java/com/google/cloud/executor/spanner/CloudExecutorImpl.java
+++ b/google-cloud-spanner-executor/src/main/java/com/google/cloud/executor/spanner/CloudExecutorImpl.java
@@ -72,6 +72,8 @@ public StreamObserver<SpannerAsyncActionRequest> executeActionAsync(
     // Create a top-level OpenTelemetry span for streaming request.
     Tracer tracer = WorkerProxy.openTelemetrySdk.getTracer(CloudClientExecutor.class.getName());
     Span span = tracer.spanBuilder("java_systest_execute_actions_stream").setNoParent().startSpan();
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("MustBeClosedChecker")
     Scope scope = span.makeCurrent();
 
     final String traceId = span.getSpanContext().getTraceId();
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java
index 6ea4510d3db..b58aa28c6d9 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java
@@ -212,6 +212,8 @@ protected boolean isRouteToLeader() {
       return false;
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     @GuardedBy("lock")
     @Override
     void beforeReadOrQueryLocked() {
@@ -456,6 +458,8 @@ void initTransaction() {
       }
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     private void initTransactionInternal(BeginTransactionRequest request) {
       try {
         Transaction transaction =
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/OpenTelemetryApiTracer.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/OpenTelemetryApiTracer.java
index 863c531de30..3b43490e3e1 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/OpenTelemetryApiTracer.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/OpenTelemetryApiTracer.java
@@ -77,6 +77,8 @@ Span getSpan() {
 
   @Override
   public Scope inScope() {
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("MustBeClosedChecker")
     final io.opentelemetry.context.Scope openTelemetryScope = span.makeCurrent();
     return openTelemetryScope::close;
   }
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Options.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Options.java
index c36f1902648..8da85252be2 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Options.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/Options.java
@@ -1025,6 +1025,8 @@ void appendToOptions(Options options) {
       options.filter = filter;
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("EqualsHashCode")
     @Override
     public boolean equals(Object o) {
       if (o == this) return true;
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java
index 0b55a893aca..9f37c53139d 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionPool.java
@@ -587,6 +587,8 @@ public PooledSessionFuture replaceSession(
       }
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     @Override
     public PooledSessionFuture denyListSession(
         RetryOnDifferentGrpcChannelException retryException, PooledSessionFuture session) {
@@ -1768,6 +1770,8 @@ public ApiFuture<Empty> asyncClose() {
       return ApiFutures.immediateFuture(Empty.getDefaultInstance());
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     @Override
     public void close() {
       synchronized (lock) {
@@ -1848,12 +1852,16 @@ public SessionImpl getDelegate() {
       return this.delegate;
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     @Override
     public void markBusy(ISpan span) {
       this.delegate.setCurrentSpan(span);
       this.state = SessionState.BUSY;
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     private void markClosing() {
       this.state = SessionState.CLOSING;
     }
@@ -2091,6 +2099,8 @@ void maintainPool() {
       removeLongRunningSessions(currTime);
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     private void removeIdleSessions(Instant currTime) {
       synchronized (lock) {
         // Determine the minimum last use time for a session to be deemed to still be alive. Remove
@@ -2190,6 +2200,8 @@ void removeLongRunningSessions(Instant currentTime) {
       }
     }
 
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     private void removeLongRunningSessions(
         final Instant currentTime,
         final InactiveTransactionRemovalOptions inactiveTransactionRemovalOptions) {
@@ -2691,6 +2703,8 @@ private void invalidateSession(PooledSession session) {
     }
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private Tuple<PooledSession, Integer> findSessionToKeepAlive(
       Queue<PooledSession> queue, Instant keepAliveThreshold, int numAlreadyChecked) {
     int numChecked = 0;
@@ -2885,6 +2899,8 @@ private void releaseSession(PooledSession session, boolean isNewSession) {
   }
 
   /** Releases a session back to the pool. This might cause one of the waiters to be unblocked. */
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private void releaseSession(
       PooledSession session, boolean isNewSession, @Nullable Integer position) {
     Preconditions.checkNotNull(session);
@@ -2945,6 +2961,8 @@ private void releaseSession(
    * running many small, quick queries using a small number of parallel threads. This can cause a
    * high TPS, without actually having a high degree of parallelism.
    */
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @VisibleForTesting
   boolean shouldRandomize() {
     return this.options.getRandomizePositionQPSThreshold() > 0
@@ -2952,6 +2970,8 @@ boolean shouldRandomize() {
         && this.numSessionsInUse >= this.numChannels;
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private boolean isUnbalanced(PooledSession session) {
     int channel = session.getChannel();
     int numChannels = sessionClient.getSpanner().getOptions().getNumChannels();
@@ -3054,10 +3074,14 @@ private void handleCreateSessionsFailure(SpannerException e, int count) {
     }
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   void setResourceNotFoundException(ResourceNotFoundException e) {
     this.resourceNotFoundException = MoreObjects.firstNonNull(this.resourceNotFoundException, e);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private void decrementPendingClosures(int count) {
     pendingClosure -= count;
     if (pendingClosure == 0) {
@@ -3070,6 +3094,8 @@ private void decrementPendingClosures(int count) {
    * {@code IllegalStateException}. The returned future blocks till all the sessions created in this
    * pool have been closed.
    */
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   ListenableFuture<Void> closeAsync(ClosedException closedException) {
     ListenableFuture<Void> retFuture = null;
     synchronized (lock) {
@@ -3269,6 +3295,8 @@ public void onSessionCreateFailure(Throwable t, int createFailureForSessionCount
    * Initializes and creates Spanner session relevant metrics using OpenCensus. When coupled with an
    * exporter, it allows users to monitor client behavior.
    */
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private void initOpenCensusMetricsCollection(
       MetricRegistry metricRegistry,
       List<LabelValue> labelValues,
@@ -3402,6 +3430,8 @@ private void initOpenCensusMetricsCollection(
    * Initializes and creates Spanner session relevant metrics using OpenTelemetry. When coupled with
    * an exporter, it allows users to monitor client behavior.
    */
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private void initOpenTelemetryMetricsCollection(
       OpenTelemetry openTelemetry,
       Attributes attributes,
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
index 8f5baca64f6..dfab163610e 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerImpl.java
@@ -375,6 +375,8 @@ public void close() {
     close(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   void close(long timeout, TimeUnit unit) {
     List<ListenableFuture<Void>> closureFutures;
     synchronized (this) {
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
index 0995c478427..be984f34914 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
@@ -1828,6 +1828,8 @@ public static void enableOpenCensusTraces() {
    * Always resets the activeTracingFramework. This variable is used for internal testing, and is
    * not a valid production scenario
    */
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @ObsoleteApi(
       "The OpenCensus project is deprecated. Use enableOpenTelemetryTraces to switch to"
           + " OpenTelemetry traces")
@@ -2023,6 +2025,8 @@ private ApiTracerFactory createApiTracerFactory(
     return new CompositeTracerFactory(apiTracerFactories);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   private ApiTracerFactory getDefaultApiTracerFactory() {
     if (isEnableApiTracing()) {
       if (activeTracingFramework == TracingFramework.OPEN_TELEMETRY) {
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/TraceWrapper.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/TraceWrapper.java
index df5874cb3c6..eeb527300c3 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/TraceWrapper.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/TraceWrapper.java
@@ -130,6 +130,8 @@ ISpan getBlankSpan() {
     }
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("MustBeClosedChecker")
   IScope withSpan(ISpan span) {
     if (SpannerOptions.getActiveTracingFramework().equals(TracingFramework.OPEN_TELEMETRY)) {
       OpenTelemetrySpan openTelemetrySpan;
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractBaseUnitOfWork.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractBaseUnitOfWork.java
index 5f4facf1489..279380b394c 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractBaseUnitOfWork.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/AbstractBaseUnitOfWork.java
@@ -401,6 +401,8 @@ public <ReqT, RespT> ApiCallContext configure(
       }
       future.addListener(
           new Runnable() {
+            // Suppressed for initial Error Prone rollout.
+            @SuppressWarnings("GuardedBy")
             @Override
             public void run() {
               synchronized (this) {
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/AbstractReadContextTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/AbstractReadContextTest.java
index eea6658d26d..e5736770268 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/AbstractReadContextTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/AbstractReadContextTest.java
@@ -303,6 +303,8 @@ public void testExecuteBatchDmlLastStatement() {
             .getLastStatements());
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("JUnit4TestNotRun")
   public void executeSqlRequestBuilderWithRequestOptions() {
     ExecuteSqlRequest request =
         context
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java
index 6ceb3e979bf..bbdfd6f8d5e 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseClientImplTest.java
@@ -2331,6 +2331,8 @@ public void singleUse() {
     DatabaseClientImpl client =
         (DatabaseClientImpl)
             spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
     assertThat(checkedOut).isEmpty();
     try (ResultSet rs = client.singleUse().executeQuery(SELECT1)) {
@@ -3919,6 +3921,8 @@ public void testCreateSessionsFailure_shouldNotPropagateToCloseMethod() {
   @Test
   public void testReadWriteTransaction_usesOptions() {
     SessionPool pool = mock(SessionPool.class);
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("DoNotMock")
     PooledSessionFuture session = mock(PooledSessionFuture.class);
     when(pool.getSession()).thenReturn(session);
     TransactionOption option = mock(TransactionOption.class);
@@ -3935,6 +3939,8 @@ public void testReadWriteTransaction_usesOptions() {
   @Test
   public void testTransactionManager_usesOptions() {
     SessionPool pool = mock(SessionPool.class);
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("DoNotMock")
     PooledSessionFuture session = mock(PooledSessionFuture.class);
     when(pool.getSession()).thenReturn(session);
     TransactionOption option = mock(TransactionOption.class);
@@ -3948,6 +3954,8 @@ public void testTransactionManager_usesOptions() {
   @Test
   public void testRunAsync_usesOptions() {
     SessionPool pool = mock(SessionPool.class);
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("DoNotMock")
     PooledSessionFuture session = mock(PooledSessionFuture.class);
     when(pool.getSession()).thenReturn(session);
     TransactionOption option = mock(TransactionOption.class);
@@ -3961,6 +3969,8 @@ public void testRunAsync_usesOptions() {
   @Test
   public void testTransactionManagerAsync_usesOptions() {
     SessionPool pool = mock(SessionPool.class);
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("DoNotMock")
     PooledSessionFuture session = mock(PooledSessionFuture.class);
     when(pool.getSession()).thenReturn(session);
     TransactionOption option = mock(TransactionOption.class);
@@ -4240,6 +4250,8 @@ public void singleUseNoAction_ClearsCheckedOutSession() {
     DatabaseClientImpl client =
         (DatabaseClientImpl)
             spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
     assertThat(checkedOut).isEmpty();
 
@@ -4255,6 +4267,8 @@ public void singleUseReadOnlyTransactionNoAction_ClearsCheckedOutSession() {
     DatabaseClientImpl client =
         (DatabaseClientImpl)
             spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
     assertThat(checkedOut).isEmpty();
 
@@ -4268,6 +4282,8 @@ public void readWriteTransactionNoAction_ClearsCheckedOutSession() {
     DatabaseClientImpl client =
         (DatabaseClientImpl)
             spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
     assertThat(checkedOut).isEmpty();
 
@@ -4281,6 +4297,8 @@ public void readOnlyTransactionNoAction_ClearsCheckedOutSession() {
     DatabaseClientImpl client =
         (DatabaseClientImpl)
             spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
     assertThat(checkedOut).isEmpty();
 
@@ -4294,6 +4312,8 @@ public void transactionManagerNoAction_ClearsCheckedOutSession() {
     DatabaseClientImpl client =
         (DatabaseClientImpl)
             spanner.getDatabaseClient(DatabaseId.of(TEST_PROJECT, TEST_INSTANCE, TEST_DATABASE));
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("GuardedBy")
     Set<PooledSessionFuture> checkedOut = client.pool.checkedOutSessions;
     assertThat(checkedOut).isEmpty();
 
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseTest.java
index dc65f738619..0f33a4e10b6 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/DatabaseTest.java
@@ -165,6 +165,8 @@ public void testUnspecifiedDialectDefaultsToGoogleStandardSqlDialect() {
     assertEquals(Dialect.GOOGLE_STANDARD_SQL, database.getDialect());
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("SetUnrecognized")
   @Test
   public void testUnrecognizedDialectThrowsException() {
     assertThrows(
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolTest.java
index b027ebbc07f..66b4a10832a 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolTest.java
@@ -808,6 +808,8 @@ public void idleSessionCleanup() throws Exception {
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void longRunningTransactionsCleanup_whenActionSetToClose_verifyInactiveSessionsClosed()
       throws Exception {
@@ -854,6 +856,8 @@ public void longRunningTransactionsCleanup_whenActionSetToClose_verifyInactiveSe
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void longRunningTransactionsCleanup_whenActionSetToWarn_verifyInactiveSessionsOpen()
       throws Exception {
@@ -902,6 +906,8 @@ public void longRunningTransactionsCleanup_whenActionSetToWarn_verifyInactiveSes
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void
       longRunningTransactionsCleanup_whenUtilisationBelowThreshold_verifyInactiveSessionsOpen()
@@ -945,6 +951,8 @@ public void longRunningTransactionsCleanup_whenActionSetToWarn_verifyInactiveSes
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void
       longRunningTransactionsCleanup_whenAllAreExpectedlyLongRunning_verifyInactiveSessionsOpen()
@@ -1011,6 +1019,8 @@ public void longRunningTransactionsCleanup_whenActionSetToWarn_verifyInactiveSes
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void longRunningTransactionsCleanup_whenBelowDurationThreshold_verifyInactiveSessionsOpen()
       throws Exception {
@@ -1056,6 +1066,8 @@ public void longRunningTransactionsCleanup_whenBelowDurationThreshold_verifyInac
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void longRunningTransactionsCleanup_whenException_doNothing() throws Exception {
     Clock clock = mock(Clock.class);
@@ -1099,6 +1111,8 @@ public void longRunningTransactionsCleanup_whenException_doNothing() throws Exce
     pool.closeAsync(new SpannerImpl.ClosedException()).get(5L, TimeUnit.SECONDS);
   }
 
+  // Suppressed for initial Error Prone rollout.
+  @SuppressWarnings("GuardedBy")
   @Test
   public void
       longRunningTransactionsCleanup_whenTaskRecurrenceBelowThreshold_verifyInactiveSessionsOpen()
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolUnbalancedTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolUnbalancedTest.java
index 5a9365eaed9..71b3d75d077 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolUnbalancedTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SessionPoolUnbalancedTest.java
@@ -49,6 +49,8 @@ static List<PooledSession> mockedSessions(int... channels) {
 
   static PooledSessionFuture mockedCheckedOutSession(int channel) {
     PooledSession session = mockedSession(channel);
+    // Suppressed for initial Error Prone rollout.
+    @SuppressWarnings("DoNotMock")
     PooledSessionFuture future = mock(PooledSessionFuture.class);
     when(future.get()).thenReturn(session);
     when(future.isDone()).thenReturn(true);
diff --git a/pom.xml b/pom.xml
index 7220e5fdffe..6e9b6340f00 100644
--- a/pom.xml
+++ b/pom.xml
@@ -54,6 +54,7 @@
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <github.global.server>github</github.global.server>
     <site.installationModule>google-cloud-spanner-parent</site.installationModule>
+    <error-prone.version>2.38.0</error-prone.version>
   </properties>
 
   <dependencyManagement>
@@ -133,6 +134,51 @@
     </dependencies>
   </dependencyManagement>
 
+  <profiles>
+    <profile>
+      <id>java9</id>
+      <activation>
+        <jdk>[9,)</jdk>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <version>3.13.0</version>
+            <configuration>
+              <encoding>UTF-8</encoding>
+              <fork>true</fork>
+              <compilerArgs>
+                <arg>-XDcompilePolicy=simple</arg>
+                <arg>--should-stop=ifError=FLOW</arg>
+                <arg>-Xplugin:ErrorProne -Xep:CheckReturnValue:OFF -Xep:ProtoBuilderReturnValueIgnored:OFF -Xep:ReturnValueIgnored:OFF -Xep:BoxedPrimitiveEquality:OFF -Xep:UnicodeInCode:OFF</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED</arg>
+                <arg>-J--add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED</arg>
+                <arg>-J--add-opens=jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED</arg>
+                <arg>-J--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED</arg>
+              </compilerArgs>
+              <annotationProcessorPaths>
+                <path>
+                  <groupId>com.google.errorprone</groupId>
+                  <artifactId>error_prone_core</artifactId>
+                  <version>${error-prone.version}</version>
+                </path>
+              </annotationProcessorPaths>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+  </profiles>
+
+
   <modules>
     <module>google-cloud-spanner</module>
     <module>grpc-google-cloud-spanner-v1</module>