Minor little cleanups (#2695)

* Remove or narrow unnecessary or broad warnings suppressions
* Shorten the lookup of annotations in Property.java
* Use Streams where they simplify or improve the processing of big loops
* Shorten a few lines with casts using var
* Improve use of generics in a few places
* Fix license header in proto generation to be consistent with project
* Avoid unnecessary reflection to load DistCp in ShellServerIT
* Remove unneeded super()

core/src/main/java/org/apache/accumulo/core/bloomfilter/BloomFilter.java

@@ -76,9 +76,7 @@ public class BloomFilter extends Filter {
   BitSet bits;
 
   /** Default constructor - use with readFields */
-  public BloomFilter() {
-    super();
-  }
+  public BloomFilter() {}
 
   /**
    * Constructor

core/src/main/java/org/apache/accumulo/core/classloader/DefaultContextClassLoaderFactory.java

@@ -32,7 +32,6 @@
 import org.apache.accumulo.core.spi.common.ContextClassLoaderFactory;
 import org.apache.accumulo.core.util.threads.ThreadPools;
 import org.apache.accumulo.core.util.threads.Threads;
-import org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -43,24 +42,33 @@
  * for all requested contexts. This class is used internally to Accumulo only, and should not be
  * used by users in their configuration.
  */
-@SuppressWarnings({"deprecation", "removal"})
 public class DefaultContextClassLoaderFactory implements ContextClassLoaderFactory {
 
   private static final AtomicBoolean isInstantiated = new AtomicBoolean(false);
   private static final Logger LOG = LoggerFactory.getLogger(DefaultContextClassLoaderFactory.class);
   private static final String className = DefaultContextClassLoaderFactory.class.getName();
 
+  @SuppressWarnings("removal")
+  private static final Property VFS_CONTEXT_CLASSPATH_PROPERTY =
+      Property.VFS_CONTEXT_CLASSPATH_PROPERTY;
+
   public DefaultContextClassLoaderFactory(final AccumuloConfiguration accConf) {
     if (!isInstantiated.compareAndSet(false, true)) {
       throw new IllegalStateException("Can only instantiate " + className + " once");
     }
     Supplier<Map<String,String>> contextConfigSupplier =
-        () -> accConf.getAllPropertiesWithPrefix(Property.VFS_CONTEXT_CLASSPATH_PROPERTY);
-    AccumuloVFSClassLoader.setContextConfig(contextConfigSupplier);
+        () -> accConf.getAllPropertiesWithPrefix(VFS_CONTEXT_CLASSPATH_PROPERTY);
+    setContextConfig(contextConfigSupplier);
     LOG.debug("ContextManager configuration set");
     startCleanupThread(accConf, contextConfigSupplier);
   }
 
+  @SuppressWarnings("deprecation")
+  private static void setContextConfig(Supplier<Map<String,String>> contextConfigSupplier) {
+    org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader
+        .setContextConfig(contextConfigSupplier);
+  }
+
   private static void startCleanupThread(final AccumuloConfiguration conf,
       final Supplier<Map<String,String>> contextConfigSupplier) {
     ScheduledFuture<?> future = ThreadPools.getClientThreadPools((t, e) -> {
@@ -69,18 +77,26 @@ private static void startCleanupThread(final AccumuloConfiguration conf,
         .scheduleWithFixedDelay(Threads.createNamedRunnable(className + "-cleanup", () -> {
           LOG.trace("{}-cleanup thread, properties: {}", className, conf);
           Set<String> contextsInUse = contextConfigSupplier.get().keySet().stream()
-              .map(p -> p.substring(Property.VFS_CONTEXT_CLASSPATH_PROPERTY.getKey().length()))
+              .map(p -> p.substring(VFS_CONTEXT_CLASSPATH_PROPERTY.getKey().length()))
               .collect(Collectors.toSet());
           LOG.trace("{}-cleanup thread, contexts in use: {}", className, contextsInUse);
-          AccumuloVFSClassLoader.removeUnusedContexts(contextsInUse);
+          removeUnusedContexts(contextsInUse);
         }), 1, 1, MINUTES);
     ThreadPools.watchNonCriticalScheduledTask(future);
     LOG.debug("Context cleanup timer started at 60s intervals");
   }
 
+  @SuppressWarnings("deprecation")
+  private static void removeUnusedContexts(Set<String> contextsInUse) {
+    org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader
+        .removeUnusedContexts(contextsInUse);
+  }
+
+  @SuppressWarnings("deprecation")
   @Override
   public ClassLoader getClassLoader(String contextName) {
-    return AccumuloVFSClassLoader.getContextClassLoader(contextName);
+    return org.apache.accumulo.start.classloader.vfs.AccumuloVFSClassLoader
+        .getContextClassLoader(contextName);
   }
 
 }

core/src/main/java/org/apache/accumulo/core/client/SampleNotPresentException.java

@@ -34,9 +34,7 @@ public SampleNotPresentException(String message) {
     super(message);
   }
 
-  public SampleNotPresentException() {
-    super();
-  }
+  public SampleNotPresentException() {}
 
   private static final long serialVersionUID = 1L;
 

core/src/main/java/org/apache/accumulo/core/client/mapred/RangeInputSplit.java

@@ -37,9 +37,7 @@
 public class RangeInputSplit extends org.apache.accumulo.core.client.mapreduce.RangeInputSplit
     implements InputSplit {
 
-  public RangeInputSplit() {
-    super();
-  }
+  public RangeInputSplit() {}
 
   public RangeInputSplit(RangeInputSplit split) throws IOException {
     super(split);

core/src/main/java/org/apache/accumulo/core/client/security/tokens/AuthenticationToken.java

@@ -94,16 +94,13 @@ public static <T extends AuthenticationToken> T deserialize(Class<T> tokenType,
      * @see #serialize(AuthenticationToken)
      */
     public static AuthenticationToken deserialize(String tokenClassName, byte[] tokenBytes) {
-      Class<? extends AuthenticationToken> tokenType = null;
       try {
         @SuppressWarnings("unchecked")
-        Class<? extends AuthenticationToken> tmpTokenType =
-            (Class<? extends AuthenticationToken>) Class.forName(tokenClassName);
-        tokenType = tmpTokenType;
+        var tokenType = (Class<? extends AuthenticationToken>) Class.forName(tokenClassName);
+        return deserialize(tokenType, tokenBytes);
       } catch (ClassNotFoundException e) {
         throw new IllegalArgumentException("Class not available " + tokenClassName, e);
       }
-      return deserialize(tokenType, tokenBytes);
     }
 
     /**

core/src/main/java/org/apache/accumulo/core/client/security/tokens/CredentialProviderToken.java

@@ -38,9 +38,7 @@ public class CredentialProviderToken extends PasswordToken {
   private String name;
   private String credentialProviders;
 
-  public CredentialProviderToken() {
-    super();
-  }
+  public CredentialProviderToken() {}
 
   public CredentialProviderToken(String name, String credentialProviders) throws IOException {
     requireNonNull(name);

core/src/main/java/org/apache/accumulo/core/clientImpl/DelegationTokenImpl.java

@@ -45,7 +45,6 @@ public class DelegationTokenImpl extends PasswordToken implements DelegationToke
   private final AuthenticationTokenIdentifier identifier;
 
   public DelegationTokenImpl() {
-    super();
     this.identifier = new AuthenticationTokenIdentifier(new TAuthenticationTokenIdentifier());
   }
 

core/src/main/java/org/apache/accumulo/core/clientImpl/IsolationException.java

@@ -29,7 +29,5 @@ public IsolationException(Exception cause) {
     super(cause);
   }
 
-  public IsolationException() {
-    super();
-  }
+  public IsolationException() {}
 }

core/src/main/java/org/apache/accumulo/core/clientImpl/mapred/BatchInputSplit.java

@@ -39,9 +39,7 @@
 public class BatchInputSplit extends org.apache.accumulo.core.clientImpl.mapreduce.BatchInputSplit
     implements InputSplit {
 
-  public BatchInputSplit() {
-    super();
-  }
+  public BatchInputSplit() {}
 
   public BatchInputSplit(BatchInputSplit split) throws IOException {
     super(split);

core/src/main/java/org/apache/accumulo/core/conf/Property.java

@@ -19,9 +19,11 @@
 package org.apache.accumulo.core.conf;
 
 import java.lang.annotation.Annotation;
+import java.util.Arrays;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.function.Predicate;
 
 import org.apache.accumulo.core.Constants;
 import org.apache.accumulo.core.classloader.ClassLoaderUtil;
@@ -39,7 +41,6 @@
 import org.apache.accumulo.core.spi.scan.SimpleScanDispatcher;
 import org.apache.accumulo.core.util.format.DefaultFormatter;
 import org.apache.accumulo.core.util.interpret.DefaultScanInterpreter;
-import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import com.google.common.base.Preconditions;
@@ -1550,21 +1551,17 @@ private void precomputeAnnotations() {
         hasAnnotation(Sensitive.class) || hasPrefixWithAnnotation(getKey(), Sensitive.class);
     isDeprecated =
         hasAnnotation(Deprecated.class) || hasPrefixWithAnnotation(getKey(), Deprecated.class);
-    if (hasAnnotation(Deprecated.class)) {
-      Deprecated dep = getAnnotation(Deprecated.class);
-      if (dep != null) {
-        deprecatedSince = dep.since();
-      }
+    Deprecated dep = getAnnotation(Deprecated.class);
+    if (dep != null) {
+      deprecatedSince = dep.since();
     }
     isExperimental =
         hasAnnotation(Experimental.class) || hasPrefixWithAnnotation(getKey(), Experimental.class);
     isReplaced =
         hasAnnotation(ReplacedBy.class) || hasPrefixWithAnnotation(getKey(), ReplacedBy.class);
-    if (hasAnnotation(ReplacedBy.class)) {
-      ReplacedBy rb = getAnnotation(ReplacedBy.class);
-      if (rb != null) {
-        replacedBy = rb.property();
-      }
+    ReplacedBy rb = getAnnotation(ReplacedBy.class);
+    if (rb != null) {
+      replacedBy = rb.property();
     }
     annotationsComputed = true;
   }
@@ -1581,76 +1578,35 @@ public static boolean isSensitive(String key) {
     Property prop = propertiesByKey.get(key);
     if (prop != null) {
       return prop.isSensitive();
-    } else {
-      for (String prefix : validPrefixes) {
-        if (key.startsWith(prefix)) {
-          if (propertiesByKey.get(prefix).isSensitive()) {
-            return true;
-          }
-        }
-      }
     }
-    return false;
+    return validPrefixes.stream().filter(key::startsWith).map(propertiesByKey::get)
+        .anyMatch(Property::isSensitive);
   }
 
   private <T extends Annotation> boolean hasAnnotation(Class<T> annotationType) {
-    Logger log = LoggerFactory.getLogger(getClass());
-    try {
-      for (Annotation a : getClass().getField(name()).getAnnotations()) {
-        if (annotationType.isInstance(a)) {
-          return true;
-        }
-      }
-    } catch (SecurityException | NoSuchFieldException e) {
-      log.error("{}", e.getMessage(), e);
-    }
-    return false;
+    return getAnnotation(annotationType) != null;
   }
 
   private <T extends Annotation> T getAnnotation(Class<T> annotationType) {
-    Logger log = LoggerFactory.getLogger(getClass());
     try {
-      for (Annotation a : getClass().getField(name()).getAnnotations()) {
-        if (annotationType.isInstance(a)) {
-          @SuppressWarnings("unchecked")
-          T uncheckedA = (T) a;
-          return uncheckedA;
-        }
-      }
+      return getClass().getField(name()).getAnnotation(annotationType);
     } catch (SecurityException | NoSuchFieldException e) {
-      log.error("{}", e.getMessage(), e);
+      LoggerFactory.getLogger(getClass()).error("{}", e.getMessage(), e);
     }
     return null;
   }
 
   private static <T extends Annotation> boolean hasPrefixWithAnnotation(String key,
       Class<T> annotationType) {
-    for (String prefix : validPrefixes) {
-      if (key.startsWith(prefix)) {
-        if (propertiesByKey.get(prefix).hasAnnotation(annotationType)) {
-          return true;
-        }
-      }
-    }
-
-    return false;
+    Predicate<Property> hasIt = prop -> prop.hasAnnotation(annotationType);
+    return validPrefixes.stream().filter(key::startsWith).map(propertiesByKey::get).anyMatch(hasIt);
   }
 
   private static final HashSet<String> validTableProperties = new HashSet<>();
   private static final HashSet<String> validProperties = new HashSet<>();
   private static final HashSet<String> validPrefixes = new HashSet<>();
   private static final HashMap<String,Property> propertiesByKey = new HashMap<>();
 
-  private static boolean isKeyValidlyPrefixed(String key) {
-    for (String prefix : validPrefixes) {
-      if (key.startsWith(prefix)) {
-        return true;
-      }
-    }
-
-    return false;
-  }
-
   /**
    * Checks if the given property and value are valid. A property is valid if the property key is
    * valid see {@link #isValidTablePropertyKey} and that the value is a valid format for the type
@@ -1676,7 +1632,8 @@ public static boolean isTablePropertyValid(final String key, final String value)
    * @return true if key is valid (recognized, or has a recognized prefix)
    */
   public static boolean isValidPropertyKey(String key) {
-    return validProperties.contains(key) || isKeyValidlyPrefixed(key);
+    return validProperties.contains(key) || validPrefixes.stream().anyMatch(key::startsWith);
+
   }
 
   /**
@@ -1828,24 +1785,24 @@ public static <T> T createInstanceFromPropertyName(AccumuloConfiguration conf, P
     // Precomputing information here avoids :
     // * Computing it each time a method is called
     // * Using synch to compute the first time a method is called
-    for (Property p : Property.values()) {
-      propertiesByKey.put(p.getKey(), p);
-      if (p.getType().equals(PropertyType.PREFIX)) {
-        validPrefixes.add(p.getKey());
-      } else {
-        validProperties.add(p.getKey());
-      }
-      // exclude prefix types (prevents setting a prefix type like table.custom or
-      // table.constraint, directly, since they aren't valid properties on their own)
-      if (!p.getType().equals(PropertyType.PREFIX)
-          && p.getKey().startsWith(Property.TABLE_PREFIX.getKey())) {
-        validTableProperties.add(p.getKey());
-      }
-    }
+    Predicate<Property> isPrefix = p -> p.getType() == PropertyType.PREFIX;
+    Arrays.stream(Property.values())
+        // record all properties by key
+        .peek(p -> propertiesByKey.put(p.getKey(), p))
+        // save all the prefix properties
+        .peek(p -> {
+          if (isPrefix.test(p))
+            validPrefixes.add(p.getKey());
+        })
+        // only use the keys for the non-prefix properties from here on
+        .filter(isPrefix.negate()).map(Property::getKey)
+        // everything left is a valid property
+        .peek(validProperties::add)
+        // but some are also valid table properties
+        .filter(k -> k.startsWith(Property.TABLE_PREFIX.getKey()))
+        .forEach(validTableProperties::add);
 
     // order is very important here the following code relies on the maps and sets populated above
-    for (Property p : Property.values()) {
-      p.precomputeAnnotations();
-    }
+    Arrays.stream(Property.values()).forEach(Property::precomputeAnnotations);
   }
 }

core/src/main/java/org/apache/accumulo/core/file/blockfile/cache/lru/CachedBlock.java

@@ -40,7 +40,7 @@ public class CachedBlock implements HeapSize, Comparable<CachedBlock> {
       ClassSize.align(ClassSize.OBJECT + (3 * ClassSize.REFERENCE) + (2 * SizeConstants.SIZEOF_LONG)
           + ClassSize.STRING + ClassSize.BYTE_BUFFER + ClassSize.REFERENCE);
 
-  public static enum BlockPriority {
+  public enum BlockPriority {
     /**
      * Accessed a single time (used for scan-resistance)
      */

core/src/main/java/org/apache/accumulo/core/file/blockfile/cache/lru/LruBlockCache.java

@@ -135,7 +135,6 @@ public class LruBlockCache extends SynchronousLoadingBlockCache implements Block
   @SuppressFBWarnings(value = "SC_START_IN_CTOR",
       justification = "bad practice to start threads in constructor; probably needs rewrite")
   public LruBlockCache(final LruBlockCacheConfiguration conf) {
-    super();
     this.conf = conf;
 
     int mapInitialSize = (int) Math.ceil(1.2 * conf.getMaxSize() / conf.getBlockSize());

core/src/main/java/org/apache/accumulo/core/file/blockfile/impl/CachableBlockFile.java

@@ -304,7 +304,6 @@ private abstract class BaseBlockLoader implements Loader {
       private boolean loadingMetaBlock;
 
       public BaseBlockLoader(boolean loadingMetaBlock) {
-        super();
         this.loadingMetaBlock = loadingMetaBlock;
       }
 

core/src/main/java/org/apache/accumulo/core/file/rfile/PrintInfo.java

@@ -151,9 +151,8 @@ public String description() {
   protected Class<? extends BiFunction<Key,Value,String>> getFormatter(String formatterClazz)
       throws ClassNotFoundException {
     @SuppressWarnings("unchecked")
-    Class<? extends BiFunction<Key,Value,String>> clazz =
-        (Class<? extends BiFunction<Key,Value,String>>) this.getClass().getClassLoader()
-            .loadClass(formatterClazz).asSubclass(BiFunction.class);
+    var clazz = (Class<? extends BiFunction<Key,Value,String>>) this.getClass().getClassLoader()
+        .loadClass(formatterClazz).asSubclass(BiFunction.class);
     return clazz;
   }
 

core/src/main/java/org/apache/accumulo/core/file/rfile/bcfile/MetaBlockAlreadyExists.java

@@ -23,8 +23,9 @@
 /**
  * Exception - Meta Block with the same name already exists.
  */
-@SuppressWarnings("serial")
 public class MetaBlockAlreadyExists extends IOException {
+  private static final long serialVersionUID = -6797037044124244666L;
+
   /**
    * Constructor
    *