diff --git a/Antlr4.Runtime/Atn/ATNConfigSet.cs b/Antlr4.Runtime/Atn/ATNConfigSet.cs
index 5049069fc..c41e8f648 100644
--- a/Antlr4.Runtime/Atn/ATNConfigSet.cs
+++ b/Antlr4.Runtime/Atn/ATNConfigSet.cs
@@ -664,45 +664,5 @@ namespace Antlr4.Runtime.Atn
                 throw new InvalidOperationException("This ATNConfigSet is read only.");
             }
         }
-
-        private sealed class ATNConfigSetIterator : IEnumerator<ATNConfig>
-        {
-            internal int index = -1;
-
-            internal bool removed = false;
-
-            public bool HasNext()
-            {
-                return this.index + 1 < this._enclosing.configs.Count;
-            }
-
-            public ATNConfig Next()
-            {
-                if (!this.HasNext())
-                {
-                    throw new InvalidOperationException();
-                }
-                this.index++;
-                this.removed = false;
-                return this._enclosing.configs[this.index];
-            }
-
-            public void Remove()
-            {
-                if (this.removed || this.index < 0 || this.index >= this._enclosing.configs.Count)
-                {
-                    throw new InvalidOperationException();
-                }
-                this._enclosing.Remove(this.index);
-                this.removed = true;
-            }
-
-            internal ATNConfigSetIterator(ATNConfigSet _enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly ATNConfigSet _enclosing;
-        }
     }
 }
diff --git a/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs b/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs
index ef2c4c2b1..c14239a89 100644
--- a/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/AbstractEdgeMap`1.cs
@@ -27,7 +27,6 @@
  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-using System.Collections;
 using System.Collections.Generic;
 using Antlr4.Runtime.Dfa;
 using Sharpen;
@@ -66,51 +65,19 @@ namespace Antlr4.Runtime.Dfa
 
         public abstract Antlr4.Runtime.Dfa.AbstractEdgeMap<T> Remove(int key);
 
-        protected internal abstract class AbstractEntrySet : AbstractSet<KeyValuePair<int
-            , T>>
-        {
-            public override bool Contains(object o)
-            {
-                if (!(o is DictionaryEntry))
-                {
-                    return false;
-                }
-                KeyValuePair<object, object> entry = (KeyValuePair<object, object>)o;
-                if (entry.Key is int)
-                {
-                    int key = (int)entry.Key;
-                    object value = entry.Value;
-                    T existing = this._enclosing._enclosing.Get(key);
-                    return value == existing || (existing != null && existing.Equals(value));
-                }
-                return false;
-            }
-
-            public override int Count
-            {
-                get
-                {
-                    return this._enclosing._enclosing.Size();
-                }
-            }
-
-            internal AbstractEntrySet(AbstractEdgeMap<T> _enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly AbstractEdgeMap<T> _enclosing;
-        }
-
         public abstract bool ContainsKey(int arg1);
 
-        public abstract ISet<KeyValuePair<int, T>> EntrySet();
-
         public abstract T Get(int arg1);
 
-        public abstract bool IsEmpty();
+        public abstract bool IsEmpty
+        {
+            get;
+        }
 
-        public abstract int Size();
+        public abstract int Count
+        {
+            get;
+        }
 
         public abstract IDictionary<int, T> ToMap();
     }
diff --git a/Antlr4.Runtime/Dfa/ArrayEdgeMap`1.cs b/Antlr4.Runtime/Dfa/ArrayEdgeMap`1.cs
index 188a550e0..12da82329 100644
--- a/Antlr4.Runtime/Dfa/ArrayEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/ArrayEdgeMap`1.cs
@@ -46,28 +46,37 @@ namespace Antlr4.Runtime.Dfa
             arrayData = (T[])new object[maxIndex - minIndex + 1];
         }
 
-        public override int Size()
+        public override int Count
         {
-            return size;
+            get
+            {
+                return size;
+            }
         }
 
-        public override bool IsEmpty()
+        public override bool IsEmpty
         {
-            return size == 0;
+            get
+            {
+                return size == 0;
+            }
         }
 
         public override bool ContainsKey(int key)
         {
-            return Get(key) != null;
+            return this[key] != null;
         }
 
-        public override T Get(int key)
+        public override T this[int key]
         {
-            if (key < minIndex || key > maxIndex)
+            get
             {
-                return null;
+                if (key < minIndex || key > maxIndex)
+                {
+                    return null;
+                }
+                return arrayData[key - minIndex];
             }
-            return arrayData[key - minIndex];
         }
 
         public override AbstractEdgeMap<T> Put(int key, T value)
@@ -98,7 +107,7 @@ namespace Antlr4.Runtime.Dfa
 
         public override AbstractEdgeMap<T> PutAll<_T0>(IEdgeMap<_T0> m)
         {
-            if (m.IsEmpty())
+            if (m.IsEmpty)
             {
                 return this;
             }
@@ -124,7 +133,7 @@ namespace Antlr4.Runtime.Dfa
                 if (m is SingletonEdgeMap<object>)
                 {
                     SingletonEdgeMap<T> other = (SingletonEdgeMap<T>)m;
-                    System.Diagnostics.Debug.Assert(!other.IsEmpty());
+                    System.Diagnostics.Debug.Assert(!other.IsEmpty);
                     return ((Antlr4.Runtime.Dfa.ArrayEdgeMap<T>)Put(other.GetKey(), other.GetValue())
                         );
                 }
@@ -159,7 +168,7 @@ namespace Antlr4.Runtime.Dfa
 
         public override IDictionary<int, T> ToMap()
         {
-            if (IsEmpty())
+            if (IsEmpty)
             {
                 return Sharpen.Collections.EmptyMap();
             }
@@ -174,99 +183,5 @@ namespace Antlr4.Runtime.Dfa
             }
             return result;
         }
-
-        public override ISet<KeyValuePair<int, T>> EntrySet()
-        {
-            return new ArrayEdgeMap.EntrySet(this);
-        }
-
-        private class EntrySet : AbstractEdgeMap.AbstractEntrySet
-        {
-            public override IEnumerator<KeyValuePair<int, T>> GetEnumerator()
-            {
-                return new ArrayEdgeMap.EntryIterator(this);
-            }
-
-            internal EntrySet(ArrayEdgeMap<T> _enclosing) : base(_enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly ArrayEdgeMap<T> _enclosing;
-        }
-
-        private class EntryIterator : IEnumerator<KeyValuePair<int, T>>
-        {
-            private int current;
-
-            private int currentIndex;
-
-            public virtual bool HasNext()
-            {
-                return this.current < this._enclosing.Size();
-            }
-
-            public virtual KeyValuePair<int, T> Next()
-            {
-                if (this.current >= this._enclosing.Size())
-                {
-                    throw new InvalidOperationException();
-                }
-                while (this._enclosing.arrayData[this.currentIndex] == null)
-                {
-                    this.currentIndex++;
-                }
-                this.current++;
-                this.currentIndex++;
-                return new _KeyValuePair_193(this);
-            }
-
-            private sealed class _KeyValuePair_193 : KeyValuePair<int, T>
-            {
-                public _KeyValuePair_193()
-                {
-                    this.key = this._enclosing._enclosing.minIndex + this._enclosing.currentIndex - 1;
-                    this.value = this._enclosing._enclosing.arrayData[this._enclosing.currentIndex - 
-                        1];
-                }
-
-                private readonly int key;
-
-                private readonly T value;
-
-                public int Key
-                {
-                    get
-                    {
-                        return this.key;
-                    }
-                }
-
-                public T Value
-                {
-                    get
-                    {
-                        return this.value;
-                    }
-                }
-
-                public T SetValue(T value)
-                {
-                    throw new NotSupportedException("Not supported yet.");
-                }
-            }
-
-            public virtual void Remove()
-            {
-                throw new NotSupportedException("Not supported yet.");
-            }
-
-            internal EntryIterator(ArrayEdgeMap<T> _enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly ArrayEdgeMap<T> _enclosing;
-        }
     }
 }
diff --git a/Antlr4.Runtime/Dfa/DFAState.cs b/Antlr4.Runtime/Dfa/DFAState.cs
index 30261cff7..457c28f2f 100644
--- a/Antlr4.Runtime/Dfa/DFAState.cs
+++ b/Antlr4.Runtime/Dfa/DFAState.cs
@@ -201,7 +201,7 @@ namespace Antlr4.Runtime.Dfa
             {
                 return null;
             }
-            return edges.Get(symbol);
+            return edges[symbol];
         }
 
         public virtual void SetTarget(int symbol, DFAState target)
@@ -238,7 +238,7 @@ namespace Antlr4.Runtime.Dfa
             {
                 invokingState = -1;
             }
-            return contextEdges.Get(invokingState);
+            return contextEdges[invokingState];
         }
 
         public virtual void SetContextTarget(int invokingState, DFAState target)
diff --git a/Antlr4.Runtime/Dfa/IEdgeMap`1.cs b/Antlr4.Runtime/Dfa/IEdgeMap`1.cs
index 1a865a698..2bcea0c03 100644
--- a/Antlr4.Runtime/Dfa/IEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/IEdgeMap`1.cs
@@ -37,14 +37,22 @@ namespace Antlr4.Runtime.Dfa
     /// <author>Sam Harwell</author>
     public interface IEdgeMap<T>
     {
-        int Size();
+        int Count
+        {
+            get;
+        }
 
-        bool IsEmpty();
+        bool IsEmpty
+        {
+            get;
+        }
 
         bool ContainsKey(int key);
 
-        [Nullable]
-        T Get(int key);
+        T this[int key]
+        {
+            get;
+        }
 
         [NotNull]
         IEdgeMap<T> Put(int key, T value);
@@ -60,8 +68,5 @@ namespace Antlr4.Runtime.Dfa
 
         [NotNull]
         IDictionary<int, T> ToMap();
-
-        [NotNull]
-        ISet<KeyValuePair<int, T>> EntrySet();
     }
 }
diff --git a/Antlr4.Runtime/Dfa/SingletonEdgeMap`1.cs b/Antlr4.Runtime/Dfa/SingletonEdgeMap`1.cs
index 56a31638b..539ff3378 100644
--- a/Antlr4.Runtime/Dfa/SingletonEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/SingletonEdgeMap`1.cs
@@ -27,7 +27,6 @@
  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-using System;
 using System.Collections.Generic;
 using Antlr4.Runtime.Dfa;
 using Sharpen;
@@ -72,14 +71,20 @@ namespace Antlr4.Runtime.Dfa
             return value;
         }
 
-        public override int Size()
+        public override int Count
         {
-            return value != null ? 1 : 0;
+            get
+            {
+                return value != null ? 1 : 0;
+            }
         }
 
-        public override bool IsEmpty()
+        public override bool IsEmpty
         {
-            return value == null;
+            get
+            {
+                return value == null;
+            }
         }
 
         public override bool ContainsKey(int key)
@@ -87,13 +92,16 @@ namespace Antlr4.Runtime.Dfa
             return key == this.key && value != null;
         }
 
-        public override T Get(int key)
+        public override T this[int key]
         {
-            if (key == this.key)
+            get
             {
-                return value;
+                if (key == this.key)
+                {
+                    return value;
+                }
+                return null;
             }
-            return null;
         }
 
         public override AbstractEdgeMap<T> Put(int key, T value)
@@ -142,97 +150,11 @@ namespace Antlr4.Runtime.Dfa
 
         public override IDictionary<int, T> ToMap()
         {
-            if (IsEmpty())
+            if (IsEmpty)
             {
                 return Sharpen.Collections.EmptyMap();
             }
             return Sharpen.Collections.SingletonMap(key, value);
         }
-
-        public override ISet<KeyValuePair<int, T>> EntrySet()
-        {
-            return new SingletonEdgeMap.EntrySet(this);
-        }
-
-        private class EntrySet : AbstractEdgeMap.AbstractEntrySet
-        {
-            public override IEnumerator<KeyValuePair<int, T>> GetEnumerator()
-            {
-                return new SingletonEdgeMap.EntryIterator(this);
-            }
-
-            internal EntrySet(SingletonEdgeMap<T> _enclosing) : base(_enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly SingletonEdgeMap<T> _enclosing;
-        }
-
-        private class EntryIterator : IEnumerator<KeyValuePair<int, T>>
-        {
-            private int current;
-
-            public virtual bool HasNext()
-            {
-                return this.current < this._enclosing.Size();
-            }
-
-            public virtual KeyValuePair<int, T> Next()
-            {
-                if (this.current >= this._enclosing.Size())
-                {
-                    throw new InvalidOperationException();
-                }
-                this.current++;
-                return new _KeyValuePair_166(this);
-            }
-
-            private sealed class _KeyValuePair_166 : KeyValuePair<int, T>
-            {
-                public _KeyValuePair_166()
-                {
-                    this.key = this._enclosing._enclosing._enclosing.key;
-                    this.value = this._enclosing._enclosing._enclosing.value;
-                }
-
-                private readonly int key;
-
-                private readonly T value;
-
-                public int Key
-                {
-                    get
-                    {
-                        return this.key;
-                    }
-                }
-
-                public T Value
-                {
-                    get
-                    {
-                        return this.value;
-                    }
-                }
-
-                public T SetValue(T value)
-                {
-                    throw new NotSupportedException("Not supported yet.");
-                }
-            }
-
-            public virtual void Remove()
-            {
-                throw new NotSupportedException("Not supported yet.");
-            }
-
-            internal EntryIterator(SingletonEdgeMap<T> _enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly SingletonEdgeMap<T> _enclosing;
-        }
     }
 }
diff --git a/Antlr4.Runtime/Dfa/SparseEdgeMap`1.cs b/Antlr4.Runtime/Dfa/SparseEdgeMap`1.cs
index 2d9578379..65abe7687 100644
--- a/Antlr4.Runtime/Dfa/SparseEdgeMap`1.cs
+++ b/Antlr4.Runtime/Dfa/SparseEdgeMap`1.cs
@@ -82,29 +82,38 @@ namespace Antlr4.Runtime.Dfa
             return keys.Length;
         }
 
-        public override int Size()
+        public override int Count
         {
-            return values.Count;
+            get
+            {
+                return values.Count;
+            }
         }
 
-        public override bool IsEmpty()
+        public override bool IsEmpty
         {
-            return values.IsEmpty();
+            get
+            {
+                return values.IsEmpty();
+            }
         }
 
         public override bool ContainsKey(int key)
         {
-            return Get(key) != null;
+            return this[key] != null;
         }
 
-        public override T Get(int key)
+        public override T this[int key]
         {
-            int index = System.Array.BinarySearch(keys, 0, Size(), key);
-            if (index < 0)
+            get
             {
-                return null;
+                int index = System.Array.BinarySearch(keys, 0, Count, key);
+                if (index < 0)
+                {
+                    return null;
+                }
+                return values[index];
             }
-            return values[index];
         }
 
         public override AbstractEdgeMap<T> Put(int key, T value)
@@ -119,7 +128,7 @@ namespace Antlr4.Runtime.Dfa
             }
             lock (values)
             {
-                int index = System.Array.BinarySearch(keys, 0, Size(), key);
+                int index = System.Array.BinarySearch(keys, 0, Count, key);
                 if (index >= 0)
                 {
                     // replace existing entry
@@ -128,14 +137,14 @@ namespace Antlr4.Runtime.Dfa
                 }
                 System.Diagnostics.Debug.Assert(index < 0 && value != null);
                 int insertIndex = -index - 1;
-                if (Size() < GetMaxSparseSize() && insertIndex == Size())
+                if (Count < GetMaxSparseSize() && insertIndex == Count)
                 {
                     // stay sparse and add new entry
                     keys[insertIndex] = key;
                     values.AddItem(value);
                     return this;
                 }
-                int desiredSize = Size() >= GetMaxSparseSize() ? GetMaxSparseSize() * 2 : GetMaxSparseSize
+                int desiredSize = Count >= GetMaxSparseSize() ? GetMaxSparseSize() * 2 : GetMaxSparseSize
                     ();
                 int space = maxIndex - minIndex + 1;
                 // SparseEdgeMap only uses less memory than ArrayEdgeMap up to half the size of the symbol space
@@ -161,7 +170,7 @@ namespace Antlr4.Runtime.Dfa
 
         public override AbstractEdgeMap<T> Remove(int key)
         {
-            int index = System.Array.BinarySearch(keys, 0, Size(), key);
+            int index = System.Array.BinarySearch(keys, 0, Count, key);
             if (index < 0)
             {
                 return this;
@@ -173,14 +182,14 @@ namespace Antlr4.Runtime.Dfa
             }
             Antlr4.Runtime.Dfa.SparseEdgeMap<T> result = new Antlr4.Runtime.Dfa.SparseEdgeMap
                 <T>(this, GetMaxSparseSize());
-            System.Array.Copy(result.keys, index + 1, result.keys, index, Size() - index - 1);
+            System.Array.Copy(result.keys, index + 1, result.keys, index, Count - index - 1);
             result.values.RemoveAt(index);
             return result;
         }
 
         public override AbstractEdgeMap<T> Clear()
         {
-            if (IsEmpty())
+            if (IsEmpty)
             {
                 return this;
             }
@@ -192,102 +201,16 @@ namespace Antlr4.Runtime.Dfa
 
         public override IDictionary<int, T> ToMap()
         {
-            if (IsEmpty())
+            if (IsEmpty)
             {
                 return Sharpen.Collections.EmptyMap();
             }
             IDictionary<int, T> result = new LinkedHashMap<int, T>();
-            for (int i = 0; i < Size(); i++)
+            for (int i = 0; i < Count; i++)
             {
                 result.Put(keys[i], values[i]);
             }
             return result;
         }
-
-        public override ISet<KeyValuePair<int, T>> EntrySet()
-        {
-            return new SparseEdgeMap.EntrySet(this);
-        }
-
-        private class EntrySet : AbstractEdgeMap.AbstractEntrySet
-        {
-            public override IEnumerator<KeyValuePair<int, T>> GetEnumerator()
-            {
-                return new SparseEdgeMap.EntryIterator(this);
-            }
-
-            internal EntrySet(SparseEdgeMap<T> _enclosing) : base(_enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly SparseEdgeMap<T> _enclosing;
-        }
-
-        private class EntryIterator : IEnumerator<KeyValuePair<int, T>>
-        {
-            private int current;
-
-            public virtual bool HasNext()
-            {
-                return this.current < this._enclosing.Size();
-            }
-
-            public virtual KeyValuePair<int, T> Next()
-            {
-                if (this.current >= this._enclosing.Size())
-                {
-                    throw new InvalidOperationException();
-                }
-                this.current++;
-                return new _KeyValuePair_226(this);
-            }
-
-            private sealed class _KeyValuePair_226 : KeyValuePair<int, T>
-            {
-                public _KeyValuePair_226()
-                {
-                    this.key = this._enclosing._enclosing.keys[this._enclosing.current - 1];
-                    this.value = this._enclosing._enclosing.values[this._enclosing.current - 1];
-                }
-
-                private readonly int key;
-
-                private readonly T value;
-
-                public int Key
-                {
-                    get
-                    {
-                        return this.key;
-                    }
-                }
-
-                public T Value
-                {
-                    get
-                    {
-                        return this.value;
-                    }
-                }
-
-                public T SetValue(T value)
-                {
-                    throw new NotSupportedException("Not supported yet.");
-                }
-            }
-
-            public virtual void Remove()
-            {
-                throw new NotSupportedException("Not supported yet.");
-            }
-
-            internal EntryIterator(SparseEdgeMap<T> _enclosing)
-            {
-                this._enclosing = _enclosing;
-            }
-
-            private readonly SparseEdgeMap<T> _enclosing;
-        }
     }
 }
diff --git a/reference/antlr4 b/reference/antlr4
index 7e785daa6..b106c4363 160000
--- a/reference/antlr4
+++ b/reference/antlr4
@@ -1 +1 @@
-Subproject commit 7e785daa65e15f9786218e5dd63ea5a3cecf67a8
+Subproject commit b106c4363db4aa913887021c7c2cf245ba7a5fa3