diff --git a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/ClassTailor.java b/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/ClassTailor.java
deleted file mode 100644
index 75d6c97..0000000
--- a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/ClassTailor.java
+++ /dev/null
@@ -1,172 +0,0 @@
-/*
- * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0, which is available at
- * http://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-package org.glassfish.jaxb.runtime.v2.bytecode;
-
-import org.glassfish.jaxb.core.Utils;
-
-import java.io.*;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-/**
- * Replaces a few constant pool tokens from a class "template" and then loads it into the VM.
- *
- * @author Kohsuke Kawaguchi
- */
-public final class ClassTailor {
-
-    private ClassTailor() {} // no instanciation please
-
-    private static final Logger logger = Utils.getClassLogger();
-
-    /**
-     * Returns the class name in the JVM format (such as "java/lang/String")
-     */
-    public static String toVMClassName( Class c ) {
-        assert !c.isPrimitive();
-        if(c.isArray())
-            // I have no idea why it is designed like this, but javap says so.
-            return toVMTypeName(c);
-        return c.getName().replace('.','/');
-    }
-
-    public static String toVMTypeName( Class c ) {
-        if(c.isArray()) {
-            // TODO: study how an array type is encoded.
-            return '['+toVMTypeName(c.getComponentType());
-        }
-        if(c.isPrimitive()) {
-            if(c==Boolean.TYPE)     return "Z";
-            if(c==Character.TYPE)   return "C";
-            if(c==Byte.TYPE)        return "B";
-            if(c==Double.TYPE)      return "D";
-            if(c==Float.TYPE)       return "F";
-            if(c==Integer.TYPE)     return "I";
-            if(c==Long.TYPE)        return "J";
-            if(c==Short.TYPE)       return "S";
-
-            throw new IllegalArgumentException(c.getName());
-        }
-        return 'L'+c.getName().replace('.','/')+';';
-    }
-
-
-
-    public static byte[] tailor( Class templateClass, String newClassName, String... replacements ) {
-        String vmname = toVMClassName(templateClass);
-        return tailor(
-            SecureLoader.getClassClassLoader(templateClass).getResourceAsStream(vmname+".class"),
-            vmname, newClassName, replacements );
-    }
-
-
-    /**
-     * Customizes a class file by replacing constant pools.
-     *
-     * @param image
-     *      The image of the template class.
-     * @param replacements
-     *      A list of pair of strings that specify the substitution
-     *      {@code String[]{search_0, replace_0, search_1, replace_1, ..., search_n, replace_n }}
-     *
-     *      The search strings found in the constant pool will be replaced by the corresponding
-     *      replacement string.
-     */
-    public static byte[] tailor( InputStream image, String templateClassName, String newClassName, String... replacements ) {
-        DataInputStream in = new DataInputStream(image);
-
-        try {
-            ByteArrayOutputStream baos = new ByteArrayOutputStream(1024);
-            DataOutputStream out = new DataOutputStream(baos);
-
-            // skip until the constant pool count
-            long l = in.readLong();
-            out.writeLong(l);
-
-            // read the constant pool size
-            short count = in.readShort();
-            out.writeShort(count);
-
-            // replace constant pools
-            for( int i=0; i<count; i++ ) {
-                byte tag = in.readByte();
-                out.writeByte(tag);
-                switch(tag) {
-                case 0:
-                    // this isn't described in the spec,
-                    // but class files often seem to have this '0' tag.
-                    // we can apparently just ignore it, but not sure
-                    // what this really means.
-                    break;
-
-                case 1: // CONSTANT_UTF8
-                    {
-                        String value = in.readUTF();
-                        if(value.equals(templateClassName))
-                            value = newClassName;
-                        else {
-                            for( int j=0; j<replacements.length; j+=2 )
-                                if(value.equals(replacements[j])) {
-                                    value = replacements[j+1];
-                                    break;
-                                }
-                        }
-                        out.writeUTF(value);
-                    }
-                break;
-
-                case 3: // CONSTANT_Integer
-                case 4: // CONSTANT_Float
-                    out.writeInt(in.readInt());
-                    break;
-
-                case 5: // CONSTANT_Long
-                case 6: // CONSTANT_Double
-                    i++; // doubles and longs take two entries
-                    out.writeLong(in.readLong());
-                    break;
-
-                case 7: // CONSTANT_Class
-                case 8: // CONSTANT_String
-                    out.writeShort(in.readShort());
-                    break;
-
-                case 9: // CONSTANT_Fieldref
-                case 10: // CONSTANT_Methodref
-                case 11: // CONSTANT_InterfaceMethodref
-                case 12: // CONSTANT_NameAndType
-                    out.writeInt(in.readInt());
-                    break;
-
-                default:
-                    throw new IllegalArgumentException("Unknown constant type "+tag);
-                }
-            }
-
-            // then copy the rest
-            byte[] buf = new byte[512];
-            int len;
-            while((len=in.read(buf))>0)
-                out.write(buf,0,len);
-
-            in.close();
-            out.close();
-
-            // by now we got the properly tailored class file image
-            return baos.toByteArray();
-
-        } catch( IOException e ) {
-            // never happen
-            logger.log(Level.WARNING,"failed to tailor",e);
-            return null;
-        }
-    }
-}
diff --git a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/SecureLoader.java b/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/SecureLoader.java
deleted file mode 100644
index 5d22ad4..0000000
--- a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/SecureLoader.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0, which is available at
- * http://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-package org.glassfish.jaxb.runtime.v2.bytecode;
-
-/**
- * Class defined for safe calls of getClassLoader methods of any kind (context/system/class
- * classloader. This MUST be package private and defined in every package which 
- * uses such invocations.
- * @author snajper
- */
-class SecureLoader {
-
-    static ClassLoader getContextClassLoader() {
-        if (System.getSecurityManager() == null) {
-            return Thread.currentThread().getContextClassLoader();
-        } else {
-            return (ClassLoader) java.security.AccessController.doPrivileged(
-                    new java.security.PrivilegedAction() {
-                        public java.lang.Object run() {
-                            return Thread.currentThread().getContextClassLoader();
-                        }
-                    });
-        }
-    }
-
-    static ClassLoader getClassClassLoader(final Class c) {
-        if (System.getSecurityManager() == null) {
-            return c.getClassLoader();
-        } else {
-            return (ClassLoader) java.security.AccessController.doPrivileged(
-                    new java.security.PrivilegedAction() {
-                        public java.lang.Object run() {
-                            return c.getClassLoader();
-                        }
-                    });
-        }
-    }
-
-    static ClassLoader getSystemClassLoader() {
-        if (System.getSecurityManager() == null) {
-            return ClassLoader.getSystemClassLoader();
-        } else {
-            return (ClassLoader) java.security.AccessController.doPrivileged(
-                    new java.security.PrivilegedAction() {
-                        public java.lang.Object run() {
-                            return ClassLoader.getSystemClassLoader();
-                        }
-                    });
-        }
-    }
-    
-}
diff --git a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/package-info.java b/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/package-info.java
deleted file mode 100644
index d7c2328..0000000
--- a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/bytecode/package-info.java
+++ /dev/null
@@ -1,14 +0,0 @@
-/*
- * Copyright (c) 2017, 2020 Oracle and/or its affiliates. All rights reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0, which is available at
- * http://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-/**
- * Code that deals with low level byte code manipulation.
- */
-package org.glassfish.jaxb.runtime.v2.bytecode;
diff --git a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/FilterTransducer.java b/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/FilterTransducer.java
index 5b2ee93..8679106 100644
--- a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/FilterTransducer.java
+++ b/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/FilterTransducer.java
@@ -1,9 +1,5 @@
 /*
-<<<<<<< HEAD:jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/FilterTransducer.java
- * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
-=======
- * Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
->>>>>>> parent of 263e92e (Revert optimization removal (#1352)):jaxb-ri/runtime/impl/src/main/java/com/sun/xml/bind/v2/runtime/FilterTransducer.java
+ * Copyright (c) 1997, 2021 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Distribution License v. 1.0, which is available at
@@ -34,30 +30,37 @@
         this.core = core;
     }
 
+    @Override
     public boolean useNamespace() {
         return core.useNamespace();
     }
 
+    @Override
     public void declareNamespace(T o, XMLSerializer w) throws AccessorException {
         core.declareNamespace(o, w);
     }
 
+    @Override
     public @NotNull CharSequence print(@NotNull T o) throws AccessorException {
         return core.print(o);
     }
 
+    @Override
     public T parse(CharSequence lexical) throws AccessorException, SAXException {
         return core.parse(lexical);
     }
 
+    @Override
     public void writeText(XMLSerializer w, T o, String fieldName) throws IOException, SAXException, XMLStreamException, AccessorException {
         core.writeText(w, o, fieldName);
     }
 
+    @Override
     public void writeLeafElement(XMLSerializer w, Name tagName, T o, String fieldName) throws IOException, SAXException, XMLStreamException, AccessorException {
         core.writeLeafElement(w,tagName,o,fieldName);
     }
 
+    @Override
     public QName getTypeName(T instance) {
         return null;
     }
diff --git a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/reflect/opt/AccessorInjector.java b/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/reflect/opt/AccessorInjector.java
deleted file mode 100644
index c3f72b0..0000000
--- a/jaxb-ri/runtime/impl/src/main/java/org/glassfish/jaxb/runtime/v2/runtime/reflect/opt/AccessorInjector.java
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
- * Copyright (c) 1997, 2020 Oracle and/or its affiliates. All rights reserved.
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0, which is available at
- * http://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-package org.glassfish.jaxb.runtime.v2.runtime.reflect.opt;
-
-import org.glassfish.jaxb.core.Utils;
-import org.glassfish.jaxb.runtime.v2.bytecode.ClassTailor;
-
-import java.io.InputStream;
-import java.util.logging.Logger;
-
-/**
- * @author Kohsuke Kawaguchi
- */
-class AccessorInjector {
-
-    private static final Logger logger = Utils.getClassLogger();
-
-    protected static final boolean noOptimize =
-        Utils.getSystemProperty(ClassTailor.class.getName()+".noOptimize")!=null;
-
-    static {
-        if(noOptimize)
-            logger.info("The optimized code generation is disabled");
-    }
-
-    /**
-     * Customizes a class file by replacing constant pools.
-     *
-     * @param templateClassName
-     *      The resource that contains the template class file.
-     * @param replacements
-     *      A list of pair of strings that specify the substitution
-     *      {@code String[]{search_0, replace_0, search_1, replace_1, ..., search_n, replace_n }
-     *
-     *      The search strings found in the constant pool will be replaced by the corresponding
-     *      replacement string.
-     */
-    private static byte[] tailor( String templateClassName, String newClassName, String... replacements ) {
-        InputStream resource;
-        if(CLASS_LOADER!=null)
-            resource = CLASS_LOADER.getResourceAsStream(templateClassName+".class");
-        else
-            resource = ClassLoader.getSystemResourceAsStream(templateClassName+".class");
-        if(resource==null)
-            return null;
-
-        return ClassTailor.tailor(resource,templateClassName,newClassName,replacements);
-    }
-
-    private static final ClassLoader CLASS_LOADER = SecureLoader.getClassClassLoader(AccessorInjector.class);
-    
-}