diff --git a/solr/core/src/java/org/apache/solr/cloud/rule/RemoteCallback.java b/solr/core/src/java/org/apache/solr/cloud/rule/RemoteCallback.java
index 5b6987dcd9f..ca3662ec21f 100644
--- a/solr/core/src/java/org/apache/solr/cloud/rule/RemoteCallback.java
+++ b/solr/core/src/java/org/apache/solr/cloud/rule/RemoteCallback.java
@@ -19,5 +19,5 @@ package org.apache.solr.cloud.rule;
 import java.util.Map;
 
 public interface RemoteCallback {
-  public void remoteCallback(SnitchContext ctx, Map<String, Object> returnedVal) ;
+  void remoteCallback(SnitchContext ctx, Map<String, Object> returnedVal);
 }
diff --git a/solr/core/src/java/org/apache/solr/handler/NestedRequestHandler.java b/solr/core/src/java/org/apache/solr/handler/NestedRequestHandler.java
index d940974d99c..947a3398183 100644
--- a/solr/core/src/java/org/apache/solr/handler/NestedRequestHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/NestedRequestHandler.java
@@ -24,5 +24,5 @@ import org.apache.solr.request.SolrRequestHandler;
 public interface NestedRequestHandler {
   /** Return a Requestandler to handle a subpath from the path this handler is registered.
    */
-  public SolrRequestHandler getSubHandler(String subPath);
+  SolrRequestHandler getSubHandler(String subPath);
 }
diff --git a/solr/core/src/java/org/apache/solr/handler/component/QueryComponent.java b/solr/core/src/java/org/apache/solr/handler/component/QueryComponent.java
index 75238ab30d3..58da1e967ed 100644
--- a/solr/core/src/java/org/apache/solr/handler/component/QueryComponent.java
+++ b/solr/core/src/java/org/apache/solr/handler/component/QueryComponent.java
@@ -794,14 +794,9 @@ public class QueryComponent extends SearchComponent
       rb.resultIds = new HashMap<>();
     }
 
-    EndResultTransformer.SolrDocumentSource solrDocumentSource = new EndResultTransformer.SolrDocumentSource() {
-
-      @Override
-      public SolrDocument retrieve(ScoreDoc doc) {
-        ShardDoc solrDoc = (ShardDoc) doc;
-        return rb.retrievedDocuments.get(solrDoc.id);
-      }
-
+    EndResultTransformer.SolrDocumentSource solrDocumentSource = doc -> {
+      ShardDoc solrDoc = (ShardDoc) doc;
+      return rb.retrievedDocuments.get(solrDoc.id);
     };
     EndResultTransformer endResultTransformer;
     if (groupSpec.isMain()) {
diff --git a/solr/core/src/java/org/apache/solr/search/grouping/endresulttransformer/EndResultTransformer.java b/solr/core/src/java/org/apache/solr/search/grouping/endresulttransformer/EndResultTransformer.java
index 40cd8d40eac..4645830e3ca 100644
--- a/solr/core/src/java/org/apache/solr/search/grouping/endresulttransformer/EndResultTransformer.java
+++ b/solr/core/src/java/org/apache/solr/search/grouping/endresulttransformer/EndResultTransformer.java
@@ -42,7 +42,7 @@ public interface EndResultTransformer {
    * Abstracts the source for {@link SolrDocument} instances.
    * The source of documents is different for a distributed search than local search
    */
-  public interface SolrDocumentSource {
+  interface SolrDocumentSource {
 
     SolrDocument retrieve(ScoreDoc doc);
 
diff --git a/solr/core/src/java/org/apache/solr/update/SolrCoreState.java b/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
index fc0bca8a125..89e286a7d67 100644
--- a/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
+++ b/solr/core/src/java/org/apache/solr/update/SolrCoreState.java
@@ -140,7 +140,7 @@ public abstract class SolrCoreState {
 
 
   public interface IndexWriterCloser {
-    public void closeWriter(IndexWriter writer) throws IOException;
+    void closeWriter(IndexWriter writer) throws IOException;
   }
 
   public abstract void doRecovery(CoreContainer cc, CoreDescriptor cd);
diff --git a/solr/core/src/test/org/apache/solr/cloud/TestCryptoKeys.java b/solr/core/src/test/org/apache/solr/cloud/TestCryptoKeys.java
index a8e206376db..72ebc5b0acb 100644
--- a/solr/core/src/test/org/apache/solr/cloud/TestCryptoKeys.java
+++ b/solr/core/src/test/org/apache/solr/cloud/TestCryptoKeys.java
@@ -46,12 +46,7 @@ public class TestCryptoKeys extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient) client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient) client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/core/TestDynamicLoading.java b/solr/core/src/test/org/apache/solr/core/TestDynamicLoading.java
index 63afe6c6e7e..6570e4ab073 100644
--- a/solr/core/src/test/org/apache/solr/core/TestDynamicLoading.java
+++ b/solr/core/src/test/org/apache/solr/core/TestDynamicLoading.java
@@ -45,12 +45,7 @@ public class TestDynamicLoading extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/handler/TestConfigReload.java b/solr/core/src/test/org/apache/solr/handler/TestConfigReload.java
index 3d89c4dd6f4..832ee1f9698 100644
--- a/solr/core/src/test/org/apache/solr/handler/TestConfigReload.java
+++ b/solr/core/src/test/org/apache/solr/handler/TestConfigReload.java
@@ -60,12 +60,7 @@ public class TestConfigReload extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/handler/TestReqParamsAPI.java b/solr/core/src/test/org/apache/solr/handler/TestReqParamsAPI.java
index a4bc0ea81f6..aca6227b639 100644
--- a/solr/core/src/test/org/apache/solr/handler/TestReqParamsAPI.java
+++ b/solr/core/src/test/org/apache/solr/handler/TestReqParamsAPI.java
@@ -43,12 +43,7 @@ public class TestReqParamsAPI extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient) client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient) client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerCloud.java b/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerCloud.java
index 76ba9c54deb..8448ec7e16f 100644
--- a/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerCloud.java
+++ b/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerCloud.java
@@ -49,12 +49,7 @@ public class TestSolrConfigHandlerCloud extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerConcurrent.java b/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerConcurrent.java
index 43b83e20c71..003900c6652 100644
--- a/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerConcurrent.java
+++ b/solr/core/src/test/org/apache/solr/handler/TestSolrConfigHandlerConcurrent.java
@@ -61,12 +61,7 @@ public class TestSolrConfigHandlerConcurrent extends AbstractFullDistribZkTestBa
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/schema/TestBulkSchemaConcurrent.java b/solr/core/src/test/org/apache/solr/schema/TestBulkSchemaConcurrent.java
index 013bd900a16..24b073fe6a8 100644
--- a/solr/core/src/test/org/apache/solr/schema/TestBulkSchemaConcurrent.java
+++ b/solr/core/src/test/org/apache/solr/schema/TestBulkSchemaConcurrent.java
@@ -60,12 +60,7 @@ public class TestBulkSchemaConcurrent  extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/schema/TestCloudManagedSchemaConcurrent.java b/solr/core/src/test/org/apache/solr/schema/TestCloudManagedSchemaConcurrent.java
index 0993ba113db..d22f11bb0a5 100644
--- a/solr/core/src/test/org/apache/solr/schema/TestCloudManagedSchemaConcurrent.java
+++ b/solr/core/src/test/org/apache/solr/schema/TestCloudManagedSchemaConcurrent.java
@@ -90,12 +90,7 @@ public class TestCloudManagedSchemaConcurrent extends AbstractFullDistribZkTestB
   
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
@@ -352,11 +347,7 @@ public class TestCloudManagedSchemaConcurrent extends AbstractFullDistribZkTestB
     final String coreUrl = (new ZkCoreNodeProps(shard1Leader)).getCoreUrl();
     assertNotNull(coreUrl);
 
-    RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-      public String getBaseURL() {
-        return coreUrl.endsWith("/") ? coreUrl.substring(0, coreUrl.length()-1) : coreUrl;
-      }
-    });
+    RestTestHarness harness = new RestTestHarness(() -> coreUrl.endsWith("/") ? coreUrl.substring(0, coreUrl.length()-1) : coreUrl);
     try {
       addFieldTypePut(harness, "fooInt", 15);
     } finally {
@@ -413,11 +404,7 @@ public class TestCloudManagedSchemaConcurrent extends AbstractFullDistribZkTestB
    */
   protected void validateZkVersion(Replica replica, int schemaZkVersion, int waitSecs, boolean retry) throws Exception {
     final String replicaUrl = (new ZkCoreNodeProps(replica)).getCoreUrl();
-    RestTestHarness testHarness = new RestTestHarness(new RESTfulServerProvider() {
-      public String getBaseURL() {
-        return replicaUrl.endsWith("/") ? replicaUrl.substring(0, replicaUrl.length()-1) : replicaUrl;
-      }
-    });
+    RestTestHarness testHarness = new RestTestHarness(() -> replicaUrl.endsWith("/") ? replicaUrl.substring(0, replicaUrl.length()-1) : replicaUrl);
     try {
       long waitMs = waitSecs * 1000L;
       if (waitMs > 0) Thread.sleep(waitMs); // wait a moment for the zk watcher to fire
diff --git a/solr/core/src/test/org/apache/solr/schema/TestCloudSchemaless.java b/solr/core/src/test/org/apache/solr/schema/TestCloudSchemaless.java
index dd5794d5615..e8a2f856022 100644
--- a/solr/core/src/test/org/apache/solr/schema/TestCloudSchemaless.java
+++ b/solr/core/src/test/org/apache/solr/schema/TestCloudSchemaless.java
@@ -81,12 +81,7 @@ public class TestCloudSchemaless extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient)client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient)client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/core/src/test/org/apache/solr/update/processor/TestNamedUpdateProcessors.java b/solr/core/src/test/org/apache/solr/update/processor/TestNamedUpdateProcessors.java
index d3304f45074..7e540c9069b 100644
--- a/solr/core/src/test/org/apache/solr/update/processor/TestNamedUpdateProcessors.java
+++ b/solr/core/src/test/org/apache/solr/update/processor/TestNamedUpdateProcessors.java
@@ -49,12 +49,7 @@ public class TestNamedUpdateProcessors extends AbstractFullDistribZkTestBase {
 
   private void setupHarnesses() {
     for (final SolrClient client : clients) {
-      RestTestHarness harness = new RestTestHarness(new RESTfulServerProvider() {
-        @Override
-        public String getBaseURL() {
-          return ((HttpSolrClient) client).getBaseURL();
-        }
-      });
+      RestTestHarness harness = new RestTestHarness(() -> ((HttpSolrClient) client).getBaseURL());
       restTestHarnesses.add(harness);
     }
   }
diff --git a/solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java b/solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java
index fe9ad08ee48..7de28b682b8 100644
--- a/solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java
+++ b/solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java
@@ -898,7 +898,7 @@ public class JavaBinCodec {
    * <p>
    * Implementors of this interface write a method to serialize a given object using an existing {@link JavaBinCodec}
    */
-  public static interface ObjectResolver {
+  public interface ObjectResolver {
     /**
      * Examine and attempt to serialize the given object, using a {@link JavaBinCodec} to write it to a stream.
      *
@@ -907,12 +907,12 @@ public class JavaBinCodec {
      * @return the object {@code o} itself if it could not be serialized, or {@code null} if the whole object was successfully serialized.
      * @see JavaBinCodec
      */
-    public Object resolve(Object o, JavaBinCodec codec) throws IOException;
+    Object resolve(Object o, JavaBinCodec codec) throws IOException;
   }
 
   public interface WritableDocFields {
-    public boolean isWritable(String name);
-    public boolean wantsAllFields();
+    boolean isWritable(String name);
+    boolean wantsAllFields();
   }
 
 
diff --git a/solr/test-framework/src/java/org/apache/solr/util/RESTfulServerProvider.java b/solr/test-framework/src/java/org/apache/solr/util/RESTfulServerProvider.java
index 7c591675c81..d4da5d9a7f4 100644
--- a/solr/test-framework/src/java/org/apache/solr/util/RESTfulServerProvider.java
+++ b/solr/test-framework/src/java/org/apache/solr/util/RESTfulServerProvider.java
@@ -16,5 +16,5 @@
  */
 package org.apache.solr.util;
 public interface RESTfulServerProvider {
-  public String getBaseURL();
+  String getBaseURL();
 }
diff --git a/solr/test-framework/src/java/org/apache/solr/util/RestTestBase.java b/solr/test-framework/src/java/org/apache/solr/util/RestTestBase.java
index 06f578206ab..b6209bff906 100644
--- a/solr/test-framework/src/java/org/apache/solr/util/RestTestBase.java
+++ b/solr/test-framework/src/java/org/apache/solr/util/RestTestBase.java
@@ -51,12 +51,7 @@ abstract public class RestTestBase extends SolrJettyTestBase {
 
     createJetty(solrHome, configFile, schemaFile, context, stopAtShutdown, extraServlets);
 
-    restTestHarness = new RestTestHarness(new RESTfulServerProvider() {
-      @Override
-      public String getBaseURL() {
-        return jetty.getBaseUrl().toString() + "/" + DEFAULT_TEST_CORENAME;
-      }
-    });
+    restTestHarness = new RestTestHarness(() -> jetty.getBaseUrl().toString() + "/" + DEFAULT_TEST_CORENAME);
   }
 
   /** Validates an update XML String is successful