diff --git a/Antlr4.Runtime/Atn/ParserATNSimulator.cs b/Antlr4.Runtime/Atn/ParserATNSimulator.cs
index fe8735f9e..892e51c47 100644
--- a/Antlr4.Runtime/Atn/ParserATNSimulator.cs
+++ b/Antlr4.Runtime/Atn/ParserATNSimulator.cs
@@ -328,7 +328,7 @@ namespace Antlr4.Runtime.Atn
                  != null && !atn.decisionToState[decision].sll);
             if (outerContext == null)
             {
-                outerContext = ParserRuleContext.EmptyContext();
+                outerContext = ParserRuleContext.EmptyContext;
             }
             SimulatorState state = null;
             if (!dfa.IsEmpty())
@@ -397,7 +397,7 @@ namespace Antlr4.Runtime.Atn
         {
             if (outerContext == null)
             {
-                outerContext = ParserRuleContext.EmptyContext();
+                outerContext = ParserRuleContext.EmptyContext;
             }
             int alt = 0;
             int m = input.Mark();
diff --git a/Antlr4.Runtime/Atn/SemanticContext.cs b/Antlr4.Runtime/Atn/SemanticContext.cs
index a0a53e2bc..888cf39d1 100644
--- a/Antlr4.Runtime/Atn/SemanticContext.cs
+++ b/Antlr4.Runtime/Atn/SemanticContext.cs
@@ -27,6 +27,7 @@
  *  (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;
 using Antlr4.Runtime.Atn;
diff --git a/Antlr4.Runtime/Atn/SimulatorState.cs b/Antlr4.Runtime/Atn/SimulatorState.cs
index 70bbc011b..0880eff01 100644
--- a/Antlr4.Runtime/Atn/SimulatorState.cs
+++ b/Antlr4.Runtime/Atn/SimulatorState.cs
@@ -47,8 +47,7 @@ namespace Antlr4.Runtime.Atn
         public SimulatorState(ParserRuleContext outerContext, DFAState s0, bool useContext
             , ParserRuleContext remainingOuterContext)
         {
-            this.outerContext = outerContext != null ? outerContext : ParserRuleContext.EmptyContext
-                ();
+            this.outerContext = outerContext != null ? outerContext : ParserRuleContext.EmptyContext;
             this.s0 = s0;
             this.useContext = useContext;
             this.remainingOuterContext = remainingOuterContext;
diff --git a/Antlr4.Runtime/ParserRuleContext.cs b/Antlr4.Runtime/ParserRuleContext.cs
index 612fed87a..2a9106bdf 100644
--- a/Antlr4.Runtime/ParserRuleContext.cs
+++ b/Antlr4.Runtime/ParserRuleContext.cs
@@ -137,10 +137,13 @@ namespace Antlr4.Runtime
         {
         }
 
-        //	public List<Integer> states;
-        public static Antlr4.Runtime.ParserRuleContext EmptyContext()
+        public static Antlr4.Runtime.ParserRuleContext EmptyContext
         {
-            return Empty;
+            get
+            {
+                //	public List<Integer> states;
+                return Empty;
+            }
         }
 
         /// <summary>COPY a ctx (I'm deliberately not using copy constructor)</summary>
@@ -368,14 +371,20 @@ namespace Antlr4.Runtime
             }
         }
 
-        public virtual IToken GetStart()
+        public virtual IToken Start
         {
-            return start;
+            get
+            {
+                return start;
+            }
         }
 
-        public virtual IToken GetStop()
+        public virtual IToken Stop
         {
-            return stop;
+            get
+            {
+                return stop;
+            }
         }
 
         /// <summary>Used for rule context info debugging during parse-time, not so much for ATN debugging
diff --git a/Antlr4.Runtime/RuleContext.cs b/Antlr4.Runtime/RuleContext.cs
index 86b43d8ed..fa7f9c231 100644
--- a/Antlr4.Runtime/RuleContext.cs
+++ b/Antlr4.Runtime/RuleContext.cs
@@ -268,7 +268,7 @@ namespace Antlr4.Runtime
 
         public string ToString<_T0>(Recognizer<_T0> recog)
         {
-            return ToString(recog, ParserRuleContext.EmptyContext());
+            return ToString(recog, ParserRuleContext.EmptyContext);
         }
 
         public string ToString(IList<string> ruleNames)
diff --git a/reference/antlr4 b/reference/antlr4
index 6743730f6..7cb2b4c68 160000
--- a/reference/antlr4
+++ b/reference/antlr4
@@ -1 +1 @@
-Subproject commit 6743730f698969a938bec3ec2c42c4728a97256c
+Subproject commit 7cb2b4c6841ec131fadca8e294668113943b91a4
diff --git a/reference/sharpen-all-options.txt b/reference/sharpen-all-options.txt
index 7b24e9920..52377cbdc 100644
--- a/reference/sharpen-all-options.txt
+++ b/reference/sharpen-all-options.txt
@@ -99,6 +99,7 @@
 -methodMapping java.io.IOException.IOException(java.lang.Throwable) Sharpen.Extensions.CreateIOException
 -fieldMapping java.util.Locale.US InvariantCulture
 -typeMapping java.lang.Comparable System.IComparable
+-typeMapping java.lang.Comparable<> System.IComparable
 -typeMapping java.util.Comparator<> System.Collections.Generic.IComparer
 -typeMapping java.util.HashSet<> System.Collections.Generic.HashSet
 -typeMapping java.util.Set<> System.Collections.Generic.ISet