Summary

Add explicit constructors to the public classes in java.lang and java.io relying on default constructors.

Problem

Using default constructors is not a good practice for official types, they allow the creation of accidental constructors and do not provide a location for javadoc.

Solution

Add the constructors to the types in question, deprecating for removal constructors that are not useful and seem to have been allowed by accident.

Specification

--- old/src/java.base/share/classes/java/io/InputStream.java    2019-09-06 11:11:22.330589001 -0700
+++ new/src/java.base/share/classes/java/io/InputStream.java    2019-09-06 11:11:22.146589001 -0700
@@ -56,6 +56,11 @@
     private static final int DEFAULT_BUFFER_SIZE = 8192;

     /**
+     * Constructor for subclasses to call.
+     */
+    public InputStream() {}
+
+    /**
      * Returns a new {@code InputStream} that reads no bytes. The returned
      * stream is initially open.  The stream is closed by calling the
      * {@code close()} method.  Subsequent calls to {@code close()} have no
--- old/src/java.base/share/classes/java/io/ObjectInputStream.java  2019-09-06 11:11:22.838589001 -0700
+++ new/src/java.base/share/classes/java/io/ObjectInputStream.java  2019-09-06 11:11:22.646589001 -0700
@@ -1321,6 +1321,10 @@
      * Provide access to the persistent fields read from the input stream.
      */
     public abstract static class GetField {
+        /**
+         * Constructor for subclasses to call.
+         */
+        public GetField() {}

         /**
          * Get the ObjectStreamClass that describes the fields in the stream.
--- old/src/java.base/share/classes/java/io/ObjectOutputStream.java 2019-09-06 11:11:23.346589001 -0700
+++ new/src/java.base/share/classes/java/io/ObjectOutputStream.java 2019-09-06 11:11:23.162589001 -0700
@@ -879,6 +879,10 @@
      * @since 1.2
      */
     public abstract static class PutField {
+        /**
+         * Constructor for subclasses to call.
+         */
+        public PutField() {}

         /**
          * Put the value of the named boolean field into the persistent field.
--- old/src/java.base/share/classes/java/io/OutputStream.java   2019-09-06 11:11:23.866589001 -0700
+++ new/src/java.base/share/classes/java/io/OutputStream.java   2019-09-06 11:11:23.674589001 -0700
@@ -47,6 +47,11 @@
  */
 public abstract class OutputStream implements Closeable, Flushable {
     /**
+     * Constructor for subclasses to call.
+     */
+    public OutputStream() {}
+
+    /**
      * Returns a new {@code OutputStream} which discards all bytes.  The
      * returned stream is initially open.  The stream is closed by calling
      * the {@code close()} method.  Subsequent calls to {@code close()} have
 --- old/src/java.base/share/classes/java/lang/InheritableThreadLocal.java  2019-09-06 11:11:24.394589001 -0700
+++ new/src/java.base/share/classes/java/lang/InheritableThreadLocal.java   2019-09-06 11:11:24.182589001 -0700
@@ -52,6 +52,11 @@

 public class InheritableThreadLocal<T> extends ThreadLocal<T> {
     /**
+     * Creates an inheritable thread local variable.
+     */
+    public InheritableThreadLocal() {}
+
+    /**
      * Computes the child's initial value for this inheritable thread-local
      * variable as a function of the parent's value at the time the child
      * thread is created.  This method is called from within the parent
   --- old/src/java.base/share/classes/java/lang/ThreadDeath.java   2019-09-06 11:11:25.486589001 -0700
    +++ new/src/java.base/share/classes/java/lang/ThreadDeath.java  2019-09-06 11:11:25.234589001 -0700
    @@ -49,4 +49,9 @@
     public class ThreadDeath extends Error {
         @java.io.Serial
         private static final long serialVersionUID = -4417128565033088268L;
    +
    +    /**
    +     * Constructs a {@code ThreadDeath}.
    +     */
    +    public ThreadDeath() {}
     }
    --- old/src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java    2019-09-06 11:11:26.846589001 -0700
    +++ new/src/java.base/share/classes/java/lang/invoke/ConstantBootstraps.java    2019-09-06 11:11:26.582589001 -0700
    @@ -40,6 +40,12 @@
      * @since 11
      */
     public final class ConstantBootstraps {
    +    /**
    +     * Do not call.
    +     */
    +    @Deprecated(forRemoval=true, since="14")
    +    public ConstantBootstraps() {}
    +
         // implements the upcall from the JVM, MethodHandleNatives.linkDynamicConstant:
         /*non-public*/
         static Object makeConstant(MethodHandle bootstrapMethod,
    --- old/src/java.base/share/classes/java/lang/reflect/Modifier.java 2019-09-06 11:11:27.538589001 -0700
    +++ new/src/java.base/share/classes/java/lang/reflect/Modifier.java 2019-09-06 11:11:27.274589001 -0700
    @@ -43,6 +43,12 @@
      * @since 1.1
      */
     public class Modifier {
    +    /**
    +     * Do not call.
    +     */
    +    @Deprecated(forRemoval=true, since="14")
    +    public Modifier() {}
    +

         /**
          * Return {@code true} if the integer argument includes the