Remove unused StringKey class

Change-Id: I43752f584d7ecec489f9dcf80954206b6b96bc32

java/com/google/gwtorm/client/StringKey.java

@@ -1,86 +0,0 @@
-// Copyright 2008 Google Inc.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package com.google.gwtorm.client;
-
-import java.io.Serializable;
-
-/**
- * Abstract key type using a single string value.
- *
- * <p>Applications should subclass this type to create their own entity-specific key classes.
- *
- * @param <P> the parent key type. Use {@link Key} if no parent key is needed.
- */
-@SuppressWarnings("serial")
-public abstract class StringKey<P extends Key<?>>
-    implements Key<P>, Serializable, Comparable<StringKey<?>> {
-  /** @return name of the entity instance. */
-  public abstract String get();
-
-  /** @param newValue the new value of this key. */
-  protected abstract void set(String newValue);
-
-  /** @return the parent key instance; null if this is a root level key. */
-  @Override
-  public P getParentKey() {
-    return null;
-  }
-
-  @Override
-  public int hashCode() {
-    int hc = get() != null ? get().hashCode() : 0;
-    if (getParentKey() != null) {
-      hc *= 31;
-      hc += getParentKey().hashCode();
-    }
-    return hc;
-  }
-
-  @Override
-  public boolean equals(final Object b) {
-    if (b == null || get() == null || b.getClass() != getClass()) {
-      return false;
-    }
-
-    final StringKey<P> q = cast(b);
-    return get().equals(q.get()) && KeyUtil.eq(getParentKey(), q.getParentKey());
-  }
-
-  @Override
-  public int compareTo(final StringKey<?> other) {
-    return get().compareTo(other.get());
-  }
-
-  @Override
-  public String toString() {
-    final StringBuffer r = new StringBuffer();
-    if (getParentKey() != null) {
-      r.append(getParentKey().toString());
-      r.append(',');
-    }
-    r.append(KeyUtil.encode(get()));
-    return r.toString();
-  }
-
-  @Override
-  public void fromString(final String in) {
-    set(KeyUtil.parseFromString(getParentKey(), in));
-  }
-
-  @SuppressWarnings("unchecked")
-  private static <A extends Key<?>> StringKey<A> cast(final Object b) {
-    return (StringKey<A>) b;
-  }
-}