7903451: JMH: Refactor internal Optional usages

Passing an empty Optional to method orAnother() of class
org.openjdk.jmh.util.Optional is a no-op.  Stop doing it in getters
getJvmArgs(), getJvmArgsAppend(), and getJvmArgsPrepend() of class
OptionsBuilder.

Refactor usage of method org.openjdk.jmh.util.Optional#orAnother in
class Runner using new method orElseGet() with lazy `Supplier`s as per
comment added in commit db1bc36 (7902576: Lazy query for current JVM
args in Runner, 2020-01-20).  Clean up imports, while we're here.

Reviewed-by: shade

jmh-core/src/main/java/org/openjdk/jmh/runner/Runner.java

@@ -42,7 +42,6 @@
 
 import java.io.*;
 import java.lang.management.ManagementFactory;
-import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
 import java.nio.channels.OverlappingFileLockException;
 import java.nio.file.Files;
@@ -475,14 +474,12 @@ private BenchmarkParams newBenchmarkParams(BenchmarkListEntry benchmark, ActionM
                 benchmark.getJvmArgsPrepend().orElse(Collections.<String>emptyList())));
 
         // We want to be extra lazy when accessing ManagementFactory, because security manager
-        // may prevent us doing so. When JMH upgrades to Java 8, replaces this with proper Optional
-        // and lazy Supplier.
-        Optional<Collection<String>> jvmArgsMid = options.getJvmArgs().orAnother(benchmark.getJvmArgs());
-        if (jvmArgsMid.hasValue()) {
-            jvmArgs.addAll(jvmArgsMid.get());
-        } else {
-            jvmArgs.addAll(ManagementFactory.getRuntimeMXBean().getInputArguments());
-        }
+        // may prevent us doing so.
+        jvmArgs.addAll(options.getJvmArgs()
+                .orElseGet(() -> benchmark.getJvmArgs()
+                .orElseGet(() -> ManagementFactory.getRuntimeMXBean().getInputArguments())
+        ));
+
 
         jvmArgs.addAll(options.getJvmArgsAppend().orElse(
                 benchmark.getJvmArgsAppend().orElse(Collections.<String>emptyList())));

jmh-core/src/main/java/org/openjdk/jmh/runner/options/OptionsBuilder.java

@@ -620,9 +620,9 @@ public ChainedOptionsBuilder jvmArgs(String... value) {
     @Override
     public Optional<Collection<String>> getJvmArgs() {
         if (otherOptions != null) {
-            return jvmArgs.orAnother(otherOptions.getJvmArgs().orAnother(Optional.<Collection<String>>none()));
+            return jvmArgs.orAnother(otherOptions.getJvmArgs());
         } else {
-            return jvmArgs.orAnother(Optional.<Collection<String>>none());
+            return jvmArgs;
         }
     }
 
@@ -639,9 +639,9 @@ public ChainedOptionsBuilder jvmArgsAppend(String... value) {
     @Override
     public Optional<Collection<String>> getJvmArgsAppend() {
         if (otherOptions != null) {
-            return jvmArgsAppend.orAnother(otherOptions.getJvmArgsAppend().orAnother(Optional.<Collection<String>>none()));
+            return jvmArgsAppend.orAnother(otherOptions.getJvmArgsAppend());
         } else {
-            return jvmArgsAppend.orAnother(Optional.<Collection<String>>none());
+            return jvmArgsAppend;
         }
     }
 
@@ -658,9 +658,9 @@ public ChainedOptionsBuilder jvmArgsPrepend(String... value) {
     @Override
     public Optional<Collection<String>> getJvmArgsPrepend() {
         if (otherOptions != null) {
-            return jvmArgsPrepend.orAnother(otherOptions.getJvmArgsPrepend().orAnother(Optional.<Collection<String>>none()));
+            return jvmArgsPrepend.orAnother(otherOptions.getJvmArgsPrepend());
         } else {
-            return jvmArgsPrepend.orAnother(Optional.<Collection<String>>none());
+            return jvmArgsPrepend;
         }
     }
 

jmh-core/src/main/java/org/openjdk/jmh/util/Optional.java

@@ -26,6 +26,7 @@
 
 import java.io.Serializable;
 import java.util.Objects;
+import java.util.function.Supplier;
 
 /**
  * Option class
@@ -51,6 +52,10 @@ public T orElse(T elseVal) {
         return (val == null) ? elseVal : val;
     }
 
+    public T orElseGet(Supplier<T> alternativeSupplier) {
+        return (val == null) ? alternativeSupplier.get() : val;
+    }
+
     public Optional<T> orAnother(Optional<T> alternative) {
         return (val == null) ? alternative : this;
     }