core, grpclb: fix import lints (#5017)

diff --git a/core/src/main/java/io/grpc/Status.java b/core/src/main/java/io/grpc/Status.java
index 1a10728..6dec565 100644
--- a/core/src/main/java/io/grpc/Status.java
+++ b/core/src/main/java/io/grpc/Status.java
@@ -227,7 +227,7 @@
   }
 
   private static final String TEST_EQUALS_FAILURE_PROPERTY = "io.grpc.Status.failOnEqualsForTest";
-  private static final boolean failOnEqualsForTest =
+  private static final boolean FAIL_ON_EQUALS_FOR_TEST =
       Boolean.parseBoolean(System.getProperty(TEST_EQUALS_FAILURE_PROPERTY, "false"));
   
   // Create the canonical list of Status instances indexed by their code values.
@@ -657,7 +657,7 @@
    */
   @Override
   public boolean equals(Object obj) {
-    assert !failOnEqualsForTest
+    assert !FAIL_ON_EQUALS_FOR_TEST
         : "Status.equals called; disable this by setting " + TEST_EQUALS_FAILURE_PROPERTY;
     return super.equals(obj);
   }
diff --git a/core/src/main/java/io/grpc/internal/AutoConfiguredLoadBalancerFactory.java b/core/src/main/java/io/grpc/internal/AutoConfiguredLoadBalancerFactory.java
index 9ff2bed..811ef86 100644
--- a/core/src/main/java/io/grpc/internal/AutoConfiguredLoadBalancerFactory.java
+++ b/core/src/main/java/io/grpc/internal/AutoConfiguredLoadBalancerFactory.java
@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Ascii;
 import io.grpc.Attributes;
 import io.grpc.ConnectivityState;
 import io.grpc.ConnectivityStateInfo;
@@ -179,7 +180,6 @@
     static LoadBalancerProvider decideLoadBalancerProvider(
         List<EquivalentAddressGroup> servers, @Nullable Map<String, Object> config)
         throws PolicyNotFoundException {
-      String policy = DEFAULT_POLICY;
       // Check for balancer addresses
       boolean haveBalancerAddress = false;
       for (EquivalentAddressGroup s : servers) {
@@ -198,7 +198,9 @@
         serviceConfigChoiceBalancingPolicy =
             ServiceConfigUtil.getLoadBalancingPolicyFromServiceConfig(config);
         if (serviceConfigChoiceBalancingPolicy != null) {
-          return getProviderOrThrow(serviceConfigChoiceBalancingPolicy.toLowerCase(),
+          // Handle ASCII specifically rather than relying on the implicit default locale of the str
+          return getProviderOrThrow(
+              Ascii.toLowerCase(serviceConfigChoiceBalancingPolicy),
               "service-config specifies load-balancing policy");
         }
       }
diff --git a/core/src/test/java/io/grpc/LoadBalancerRegistryTest.java b/core/src/test/java/io/grpc/LoadBalancerRegistryTest.java
index b6c227b..7729c73 100644
--- a/core/src/test/java/io/grpc/LoadBalancerRegistryTest.java
+++ b/core/src/test/java/io/grpc/LoadBalancerRegistryTest.java
@@ -24,8 +24,11 @@
 import java.util.Arrays;
 import java.util.List;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
 
 /** Unit tests for {@link LoadBalancerRegistry}. */
+@RunWith(JUnit4.class)
 public class LoadBalancerRegistryTest {
   @Test
   public void getClassesViaHardcoded_classesPresent() throws Exception {
diff --git a/core/src/test/java/io/grpc/LoadBalancerTest.java b/core/src/test/java/io/grpc/LoadBalancerTest.java
index 8b7e469..dc21bda 100644
--- a/core/src/test/java/io/grpc/LoadBalancerTest.java
+++ b/core/src/test/java/io/grpc/LoadBalancerTest.java
@@ -19,10 +19,8 @@
 import static com.google.common.truth.Truth.assertThat;
 import static org.mockito.Mockito.mock;
 
-import io.grpc.ClientStreamTracer;
 import io.grpc.LoadBalancer.PickResult;
 import io.grpc.LoadBalancer.Subchannel;
-import io.grpc.Status;
 import java.net.SocketAddress;
 import java.util.Arrays;
 import java.util.List;
diff --git a/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java b/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java
index 782da44..293d020 100644
--- a/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java
+++ b/core/src/test/java/io/grpc/internal/ManagedChannelImplIdlenessTest.java
@@ -83,7 +83,6 @@
   private final FakeClock oobExecutor = new FakeClock();
   private static final String AUTHORITY = "fakeauthority";
   private static final String USER_AGENT = "fakeagent";
-  private static final ProxyParameters NO_PROXY = null;
   private static final long IDLE_TIMEOUT_SECONDS = 30;
   private ManagedChannelImpl channel;
 
diff --git a/core/src/test/java/io/grpc/internal/RoundRobinLoadBalancerTest.java b/core/src/test/java/io/grpc/internal/RoundRobinLoadBalancerTest.java
index 96a72a6..7bdbef3 100644
--- a/core/src/test/java/io/grpc/internal/RoundRobinLoadBalancerTest.java
+++ b/core/src/test/java/io/grpc/internal/RoundRobinLoadBalancerTest.java
@@ -59,7 +59,6 @@
 import io.grpc.Metadata;
 import io.grpc.Metadata.Key;
 import io.grpc.Status;
-import io.grpc.internal.GrpcAttributes;
 import io.grpc.internal.RoundRobinLoadBalancer.EmptyPicker;
 import io.grpc.internal.RoundRobinLoadBalancer.ReadyPicker;
 import io.grpc.internal.RoundRobinLoadBalancer.Ref;
@@ -88,11 +87,13 @@
 /** Unit test for {@link RoundRobinLoadBalancer}. */
 @RunWith(JUnit4.class)
 public class RoundRobinLoadBalancerTest {
-  private RoundRobinLoadBalancer loadBalancer;
-  private List<EquivalentAddressGroup> servers = Lists.newArrayList();
-  private Map<List<EquivalentAddressGroup>, Subchannel> subchannels = Maps.newLinkedHashMap();
   private static final Attributes.Key<String> MAJOR_KEY = Attributes.Key.create("major-key");
-  private Attributes affinity = Attributes.newBuilder().set(MAJOR_KEY, "I got the keys").build();
+
+  private RoundRobinLoadBalancer loadBalancer;
+  private final List<EquivalentAddressGroup> servers = Lists.newArrayList();
+  private final Map<List<EquivalentAddressGroup>, Subchannel> subchannels = Maps.newLinkedHashMap();
+  private final Attributes affinity =
+      Attributes.newBuilder().set(MAJOR_KEY, "I got the keys").build();
 
   @Captor
   private ArgumentCaptor<SubchannelPicker> pickerCaptor;
diff --git a/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java b/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java
index 64ade74..7ccd830 100644
--- a/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java
+++ b/grpclb/src/test/java/io/grpc/grpclb/GrpclbLoadBalancerTest.java
@@ -1167,11 +1167,10 @@
     inOrder.verify(helper).createOobChannel(eq(resolutionList.get(1)), eq(lbAuthority(0)));
 
     // Attempted to connect to balancer
-    assertEquals(1, fakeOobChannels.size());
-    ManagedChannel oobChannel = fakeOobChannels.poll();
+    assertThat(fakeOobChannels).hasSize(1);
     verify(mockLbService).balanceLoad(lbResponseObserverCaptor.capture());
     StreamObserver<LoadBalanceResponse> lbResponseObserver = lbResponseObserverCaptor.getValue();
-    assertEquals(1, lbRequestObservers.size());
+    assertThat(lbRequestObservers).hasSize(1);
     StreamObserver<LoadBalanceRequest> lbRequestObserver = lbRequestObservers.poll();
 
     verify(lbRequestObserver).onNext(
@@ -1199,8 +1198,7 @@
 
     // A new stream is created
     verify(mockLbService, times(2)).balanceLoad(lbResponseObserverCaptor.capture());
-    lbResponseObserver = lbResponseObserverCaptor.getValue();
-    assertEquals(1, lbRequestObservers.size());
+    assertThat(lbRequestObservers).hasSize(1);
     lbRequestObserver = lbRequestObservers.poll();
     verify(lbRequestObserver).onNext(
         eq(LoadBalanceRequest.newBuilder().setInitialRequest(