Remove ICharSequence from OpenStringBuilder

Author: paulirwin

src/Lucene.Net.Analysis.Common/Analysis/Util/OpenStringBuilder.cs

@@ -40,7 +40,7 @@ namespace Lucene.Net.Analysis.Util
     /// <para />
     /// This type also implements <see cref="ISpanAppendable"/> to allow for efficient appending of <see cref="ReadOnlySpan{T}"/>.
     /// </remarks>
-    public class OpenStringBuilder : IAppendable, ISpanAppendable, ICharSequence, IBufferWriter<char>
+    public class OpenStringBuilder : IAppendable, ISpanAppendable, IBufferWriter<char>
     {
         protected char[] m_buf;
         protected int m_len;
@@ -50,8 +50,6 @@ public OpenStringBuilder()
         {
         }
 
-        bool ICharSequence.HasValue => m_buf != null;
-
         public OpenStringBuilder(int size)
         {
             // LUCENENET specific - validate argument

src/Lucene.Net.Analysis.ICU/Analysis/Icu/ICUNormalizer2CharFilter.cs

@@ -187,9 +187,9 @@ private int ReadFromIoNormalizeUptoBoundary()
 
             while (checkedInputBoundary <= bufLen - 1)
             {
-                int charLen = Character.CharCount(inputBuffer.CodePointAt(checkedInputBoundary));
+                int charLen = Character.CharCount(inputBuffer.Array.CodePointAt(checkedInputBoundary));
                 checkedInputBoundary += charLen;
-                if (checkedInputBoundary < bufLen && normalizer.HasBoundaryBefore(inputBuffer
+                if (checkedInputBoundary < bufLen && normalizer.HasBoundaryBefore(inputBuffer.Array
                   .CodePointAt(checkedInputBoundary)))
                 {
                     foundBoundary = true;