jruby
diff --git a/core/src/main/java/org/jruby/RubyEnumerable.java b/core/src/main/java/org/jruby/RubyEnumerable.java
@@ -1981,7 +1981,7 @@ public static IRubyObject zipEnumNext(ThreadContext context, IRubyObject arg) {
     public static IRubyObject group_by(ThreadContext context, IRubyObject self, final Block block) {
         if (!block.isGiven()) return enumeratorizeWithSize(context, self, "group_by", RubyEnumerable::size);
 
-        final RubyHash result = new RubyHash(context.runtime);
+        final RubyHash result = RubyHash.newHash(context.runtime);
 
         callEach(context, eachSite(context), self, Signature.OPTIONAL, (ctx, largs, blk) -> {
             IRubyObject larg = packEnumValues(ctx, largs);

diff --git a/core/src/main/java/org/jruby/RubyGlobal.java b/core/src/main/java/org/jruby/RubyGlobal.java
@@ -736,6 +736,7 @@ public static class StringOnlyRubyHash extends RubyHash {
         // the op_aset to also update the real ENV map via setenv/unsetenv.
         private final boolean updateRealENV;
 
+        @SuppressWarnings(value = {"deprecation", "removal"})
         public StringOnlyRubyHash(Ruby runtime, Map<RubyString, RubyString> valueMap, IRubyObject defaultValue, boolean updateRealENV) {
             super(runtime, valueMap, defaultValue);
             this.updateRealENV = updateRealENV;

diff --git a/core/src/main/java/org/jruby/RubyHash.java b/core/src/main/java/org/jruby/RubyHash.java
@@ -138,6 +138,7 @@ public class RubyHash extends RubyObject implements Map {
     public static final int COMPARE_BY_IDENTITY_F = ObjectFlags.COMPARE_BY_IDENTITY_F;
     public static final int RUBY2_KEYWORD_F = ObjectFlags.RUBY2_KEYWORD_F;
 
+    @SuppressWarnings("removal")
     public static RubyClass createHashClass(ThreadContext context, RubyClass Object, RubyModule Enumerable) {
         return defineClass(context, "Hash", Object, RubyHash::new).
                 reifiedClass(RubyHash.class).
@@ -212,6 +213,7 @@ public static final RubyHash newHash(Ruby runtime) {
     /** rb_hash_new
      *
      */
+    @SuppressWarnings("deprecation")
     public static final RubyHash newSmallHash(Ruby runtime) {
         return new RubyHash(runtime, 1);
     }
@@ -226,6 +228,23 @@ public static RubyHash newHash(Ruby runtime, IRubyObject key, IRubyObject value)
         return kwargs;
     }
 
+    @SuppressWarnings("deprecation")
+    public static RubyHash newHash(Ruby runtime, IRubyObject defaultValue) {
+        return new RubyHash(runtime, defaultValue);
+    }
+
+    @SuppressWarnings("deprecation")
+    public static RubyHash newHash(Ruby runtime, int buckets) {
+        return new RubyHash(runtime, buckets);
+    }
+
+    @SuppressWarnings("deprecation")
+    public static RubyHash newHash(Ruby runtime, IRubyObject defaultValue, int buckets) {
+        RubyHash hash = new RubyHash(runtime, buckets, true);
+        hash.ifNone = defaultValue;
+        return hash;
+    }
+
     /** rb_hash_new
      *
      */
@@ -256,26 +275,31 @@ private static void copyFrom(RubyHash self, RubyHash other, boolean identity) {
         self.setComparedByIdentity(identity);
     }
 
+    @Deprecated(since = "10.0.6.0", forRemoval = true)
     public RubyHash(Ruby runtime, RubyClass klass) {
         super(runtime, klass);
         this.ifNone = UNDEF;
         allocFirst();
     }
 
+    @Deprecated(since = "10.0.6.0", forRemoval = true)
     public RubyHash(Ruby runtime, int buckets) {
         this(runtime, UNDEF, buckets);
     }
 
+    @Deprecated(since = "10.0.6.0", forRemoval = true)
     public RubyHash(Ruby runtime) {
         this(runtime, UNDEF);
     }
 
+    @Deprecated(since = "10.0.6.0", forRemoval = true)
     public RubyHash(Ruby runtime, IRubyObject defaultValue) {
         super(runtime, runtime.getHash());
         this.ifNone = defaultValue;
         allocFirst();
     }
 
+    @Deprecated(since = "10.0.6.0", forRemoval = true)
     public RubyHash(Ruby runtime, IRubyObject defaultValue, int buckets) {
         this(runtime, buckets, true);
         this.ifNone = defaultValue;
@@ -301,6 +325,7 @@ protected RubyHash(Ruby runtime, RubyClass metaClass, IRubyObject defaultValue,
     }
 
     // TODO should this be deprecated ? (to be efficient, internals should deal with RubyHash directly)
+    @Deprecated(since = "10.0.3.0", forRemoval = true)
     public RubyHash(Ruby runtime, Map valueMap, IRubyObject defaultValue) {
         super(runtime, runtime.getHash());
         this.ifNone = defaultValue;

diff --git a/core/src/main/java/org/jruby/api/Create.java b/core/src/main/java/org/jruby/api/Create.java
@@ -196,7 +196,7 @@ public static RubyArray<?> newArray(ThreadContext context, Collection<? extends
      */
     // MRI: rb_hash_new
     public static RubyHash newHash(ThreadContext context) {
-        return new RubyHash(context.runtime);
+        return RubyHash.newHash(context.runtime);
     }
 
     /**
@@ -224,7 +224,7 @@ public static RubyHash newEmptyHash(ThreadContext context) {
      */
     // MRI: rb_hash_new
     public static RubyHash newSmallHash(ThreadContext context) {
-        return new RubyHash(context.runtime, 1);
+        return RubyHash.newHash(context.runtime, 1);
     }
 
     /**
@@ -237,7 +237,7 @@ public static RubyHash newSmallHash(ThreadContext context) {
      */
     // MRI: rb_hash_new
     public static RubyHash newSmallHash(ThreadContext context, IRubyObject key, IRubyObject value) {
-        RubyHash hash = new RubyHash(context.runtime, 1);
+        RubyHash hash = RubyHash.newHash(context.runtime, 1);
         hash.fastASetSmall(context.runtime, key, value, true);
         return hash;
     }

diff --git a/core/src/main/java/org/jruby/ext/rbconfig/RbConfigLibrary.java b/core/src/main/java/org/jruby/ext/rbconfig/RbConfigLibrary.java
@@ -236,7 +236,7 @@ public void load(Ruby runtime, boolean wrap) {
                 defineConstant(context, "DESTDIR", destDir);                            // DESTDIR on make install.
 
         // The hash configurations stored.
-        final RubyHash CONFIG = new RubyHash(runtime, 48);
+        final RubyHash CONFIG = RubyHash.newHash(runtime, 48);
 
         CONFIG.fastASetCheckString(runtime, newString(context, "DESTDIR"), destDir);
 
@@ -392,7 +392,7 @@ public void load(Ruby runtime, boolean wrap) {
 
 
         // TODO CONFIG and MAKEFILE_CONFIG seems to be the same Hash in Ruby 2.5
-        final RubyHash mkmfHash = new RubyHash(runtime, 64);
+        final RubyHash mkmfHash = RubyHash.newHash(runtime, 64);
 
         setConfig(context, mkmfHash, "libdir", vendorDirGeneral);
         setConfig(context, mkmfHash, "arch", "java");

diff --git a/core/src/main/java/org/jruby/ext/ripper/RubyRipper.java b/core/src/main/java/org/jruby/ext/ripper/RubyRipper.java
@@ -72,7 +72,7 @@ private static void defineLexStateConstants(ThreadContext context, RubyClass rip
 
     // Creates mapping table of token to arity for on_* method calls for the scanner support
     private static RubyHash createScannerEventTable(ThreadContext context) {
-        RubyHash hash = new RubyHash(context.runtime);
+        RubyHash hash = RubyHash.newHash(context.runtime);
 
         hash.fastASet(asSymbol(context, "CHAR"), asFixnum(context, 1));
         hash.fastASet(asSymbol(context, "__end__"), asFixnum(context, 1));
@@ -131,7 +131,7 @@ private static RubyHash createScannerEventTable(ThreadContext context) {
 
     // Creates mapping table of token to arity for on_* method calls for the parser support    
     private static RubyHash createParserEventTable(ThreadContext context) {
-        RubyHash hash = new RubyHash(context.runtime);
+        RubyHash hash = RubyHash.newHash(context.runtime);
 
         hash.fastASet(asSymbol(context, "BEGIN"), asFixnum(context, 1));
         hash.fastASet(asSymbol(context, "END"), asFixnum(context, 1));

diff --git a/core/src/main/java/org/jruby/ext/set/RubySet.java b/core/src/main/java/org/jruby/ext/set/RubySet.java
@@ -138,15 +138,15 @@ private RubySet(Ruby runtime, RubyHash hash) {
     // ... this is important with Rails using Sprockets at its marshalling Set instances
 
     final void allocHash(final ThreadContext context) {
-        setHash(new RubyHash(context.runtime, context.fals));
+        setHash(RubyHash.newHash(context.runtime, context.fals));
     }
 
     final void allocHash(final Ruby runtime) {
-        setHash(new RubyHash(runtime, runtime.getFalse()));
+        setHash(RubyHash.newHash(runtime, runtime.getFalse()));
     }
 
     final void allocHash(final ThreadContext context, final int size) {
-        setHash(new RubyHash(context.runtime, context.fals, size));
+        setHash(RubyHash.newHash(context.runtime, context.fals, size));
     }
 
     final void setHash(final RubyHash hash) {
@@ -918,7 +918,7 @@ public RubyFixnum hash(ThreadContext context) { // @hash.hash
     public IRubyObject classify(ThreadContext context, final Block block) {
         if (!block.isGiven()) return enumeratorizeWithSize(context, this, "classify", RubySet::size);
 
-        final RubyHash h = new RubyHash(context.runtime, size());
+        final RubyHash h = RubyHash.newHash(context.runtime, size());
 
         for ( IRubyObject i : elementsOrdered() ) {
             final IRubyObject key = block.yield(context, i);
@@ -1036,6 +1036,7 @@ static DivideTSortHash newInstance(final ThreadContext context) {
             return new DivideTSortHash(context.runtime, klass);
         }
 
+        @SuppressWarnings("removal")
         DivideTSortHash(final Ruby runtime, final RubyClass metaClass) {
             super(runtime, metaClass);
         }

diff --git a/core/src/main/java/org/jruby/ir/targets/indy/HashBootstrap.java b/core/src/main/java/org/jruby/ir/targets/indy/HashBootstrap.java
@@ -86,7 +86,7 @@ public static CallSite kwargsHash(MethodHandles.Lookup lookup, String name, Meth
 
     public static RubyHash hash(ThreadContext context, IRubyObject[] pairs) {
         Ruby runtime = context.runtime;
-        RubyHash hash = new RubyHash(runtime, pairs.length / 2 + 1);
+        RubyHash hash = RubyHash.newHash(runtime, pairs.length / 2 + 1);
         for (int i = 0; i < pairs.length;) {
             hash.fastASetCheckString(runtime, pairs[i++], pairs[i++]);
         }

diff --git a/core/src/main/java/org/jruby/java/proxies/MapJavaProxy.java b/core/src/main/java/org/jruby/java/proxies/MapJavaProxy.java
@@ -344,7 +344,7 @@ public IRubyObject shift(ThreadContext context) {
         @Override
         public RubyHash to_hash(ThreadContext context) {
             final Ruby runtime = context.runtime;
-            final RubyHash hash = new RubyHash(runtime);
+            final RubyHash hash = RubyHash.newHash(runtime);
             @SuppressWarnings("unchecked")
             Set<Map.Entry> entries = mapDelegate().entrySet();
             for ( Map.Entry entry : entries ) {

diff --git a/core/src/test/java/org/jruby/test/TestRubyHash.java b/core/src/test/java/org/jruby/test/TestRubyHash.java
@@ -185,7 +185,7 @@ public void testRestructuring() throws Exception {
     }
 
     public void testGet() {
-        RubyHash rubyHash = new RubyHash(Ruby.getGlobalRuntime());
+        RubyHash rubyHash = RubyHash.newHash(Ruby.getGlobalRuntime());
         assertEquals(null, rubyHash.get("Non matching key"));
     }