Remove unused empty constructors from suggestions classes (#37295)

We recently migrated suggestions to `Writeable`. That allows us to also
clean up empty constructors and methods that called them as they are no
longer needed. They are replaced by constructors that accept a
`StreamInput` instance.

plugins/examples/custom-suggester/src/main/java/org/elasticsearch/example/customsuggester/CustomSuggestion.java

@@ -77,11 +77,6 @@ public class CustomSuggestion extends Suggest.Suggestion<CustomSuggestion.Entry>
         return dummy;
     }
 
-    @Override
-    protected Entry newEntry() {
-        return new Entry();
-    }
-
     @Override
     protected Entry newEntry(StreamInput in) throws IOException {
         return new Entry(in);
@@ -123,11 +118,6 @@ public class CustomSuggestion extends Suggest.Suggestion<CustomSuggestion.Entry>
             out.writeString(dummy);
         }
 
-        @Override
-        protected Option newOption() {
-            return new Option();
-        }
-
         @Override
         protected Option newOption(StreamInput in) throws IOException {
             return new Option(in);
@@ -178,8 +168,6 @@ public class CustomSuggestion extends Suggest.Suggestion<CustomSuggestion.Entry>
 
             private String dummy;
 
-            public Option() {}
-
             public Option(Text text, float score, String dummy) {
                 super(text, score);
                 this.dummy = dummy;

server/src/main/java/org/elasticsearch/search/suggest/Suggest.java

@@ -33,7 +33,6 @@ import org.elasticsearch.common.text.Text;
 import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentParserUtils;
 import org.elasticsearch.rest.action.search.RestSearchAction;
@@ -46,7 +45,6 @@ import org.elasticsearch.search.suggest.term.TermSuggestion;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -78,10 +76,6 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
 
     private Map<String, Suggestion<? extends Entry<? extends Option>>> suggestMap;
 
-    private Suggest() {
-        this(Collections.emptyList());
-    }
-
     public Suggest(List<Suggestion<? extends Entry<? extends Option>>> suggestions) {
         // we sort suggestions by their names to ensure iteration over suggestions are consistent
         // this is needed as we need to fill in suggestion docs in SearchPhaseController#sortDocs
@@ -259,16 +253,11 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
      */
     public abstract static class Suggestion<T extends Suggestion.Entry> implements Iterable<T>, NamedWriteable, ToXContentFragment {
 
-        private static final String NAME = "suggestion";
-
         public static final int TYPE = 0;
-        protected String name;
+        protected final String name;
-        protected int size;
+        protected final int size;
         protected final List<T> entries = new ArrayList<>(5);
 
-        protected Suggestion() {
-        }
-
         public Suggestion(String name, int size) {
             this.name = name;
             this.size = size; // The suggested term size specified in request, only used for merging shard responses
@@ -380,7 +369,6 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
             }
         }
 
-        protected abstract T newEntry();
         protected abstract T newEntry(StreamInput in) throws IOException;
 
         @Override
@@ -608,7 +596,6 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
                 return Objects.hash(text, offset, length, options);
             }
 
-            protected abstract O newOption();
             protected abstract O newOption(StreamInput in) throws IOException;
 
             @Override
@@ -653,8 +640,8 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
                 public static final ParseField SCORE = new ParseField("score");
                 public static final ParseField COLLATE_MATCH = new ParseField("collate_match");
 
-                private Text text;
+                private final Text text;
-                private Text highlighted;
+                private final Text highlighted;
                 private float score;
                 private Boolean collateMatch;
 
@@ -673,8 +660,6 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
                     this(text, null, score);
                 }
 
-                public Option() {}
-
                 public Option(StreamInput in) throws IOException {
                     text = in.readText();
                     score = in.readFloat();
@@ -776,14 +761,6 @@ public class Suggest implements Iterable<Suggest.Suggestion<? extends Entry<? ex
 
     @Override
     public String toString() {
-        try {
+        return Strings.toString(this, true, true);
-            XContentBuilder builder = XContentFactory.jsonBuilder().prettyPrint();
-            builder.startObject();
-            toXContent(builder, EMPTY_PARAMS);
-            builder.endObject();
-            return Strings.toString(builder);
-        } catch (IOException e) {
-            return "{ \"error\" : \"" + e.getMessage() + "\"}";
-        }
     }
 }

server/src/main/java/org/elasticsearch/search/suggest/completion/CompletionSuggestion.java

@@ -71,11 +71,8 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
 
     private boolean skipDuplicates;
 
-    public CompletionSuggestion() {
-    }
-
     /**
-     * Ctr
+     * Creates a completion suggestion given its name, size and whether it should skip duplicates
      * @param name The name for the suggestions
      * @param size The number of suggestions to return
      * @param skipDuplicates Whether duplicate suggestions should be filtered out
@@ -235,11 +232,6 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
         return TYPE;
     }
 
-    @Override
-    protected Entry newEntry() {
-        return new Entry();
-    }
-
     @Override
     protected Entry newEntry(StreamInput in) throws IOException {
         return new Entry(in);
@@ -251,17 +243,12 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
             super(text, offset, length);
         }
 
-        Entry() {}
+        private Entry() {}
 
         public Entry(StreamInput in) throws IOException {
             super(in);
         }
 
-        @Override
-        protected Option newOption() {
-            return new Option();
-        }
-
         @Override
         protected Option newOption(StreamInput in) throws IOException {
             return new Option(in);
@@ -280,8 +267,8 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
         }
 
         public static class Option extends Suggest.Suggestion.Entry.Option {
-            private Map<String, Set<String>> contexts = Collections.emptyMap();
+            private final Map<String, Set<String>> contexts;
-            private ScoreDoc doc;
+            private final ScoreDoc doc;
             private SearchHit hit;
 
             public static final ParseField CONTEXTS = new ParseField("contexts");
@@ -292,10 +279,6 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
                 this.contexts = Objects.requireNonNull(contexts, "context map cannot be null");
             }
 
-            protected Option() {
-                super();
-            }
-
             public Option(StreamInput in) throws IOException {
                 super(in);
                 this.doc = Lucene.readScoreDoc(in);
@@ -455,5 +438,4 @@ public final class CompletionSuggestion extends Suggest.Suggestion<CompletionSug
             }
         }
     }
-
 }

server/src/main/java/org/elasticsearch/search/suggest/phrase/PhraseSuggestion.java

@@ -24,7 +24,6 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.text.Text;
 import org.elasticsearch.common.xcontent.ConstructingObjectParser;
-import org.elasticsearch.common.xcontent.ContextParser;
 import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.search.suggest.Suggest;
@@ -44,8 +43,6 @@ public class PhraseSuggestion extends Suggest.Suggestion<PhraseSuggestion.Entry>
     @Deprecated
     public static final int TYPE = 3;
 
-    public PhraseSuggestion() {}
-
     public PhraseSuggestion(String name, int size) {
         super(name, size);
     }
@@ -64,11 +61,6 @@ public class PhraseSuggestion extends Suggest.Suggestion<PhraseSuggestion.Entry>
         return TYPE;
     }
 
-    @Override
-    protected Entry newEntry() {
-        return new Entry();
-    }
-
     @Override
     protected Entry newEntry(StreamInput in) throws IOException {
         return new Entry(in);
@@ -132,19 +124,13 @@ public class PhraseSuggestion extends Suggest.Suggestion<PhraseSuggestion.Entry>
 
         static {
             declareCommonFields(PARSER);
-            PARSER.declareObjectArray(Entry::addOptions, (ContextParser<Void, Option>) (p, c) -> Option.fromXContent(p),
+            PARSER.declareObjectArray(Entry::addOptions, (p, c) -> Option.fromXContent(p), new ParseField(OPTIONS));
-                    new ParseField(OPTIONS));
         }
 
         public static Entry fromXContent(XContentParser parser) {
             return PARSER.apply(parser, null);
         }
 
-        @Override
-        protected Option newOption() {
-            return new Option();
-        }
-
         @Override
         protected Option newOption(StreamInput in) throws IOException {
             return new Option(in);
@@ -169,10 +155,6 @@ public class PhraseSuggestion extends Suggest.Suggestion<PhraseSuggestion.Entry>
 
         public static class Option extends Suggestion.Entry.Option {
 
-            public Option() {
-                super();
-            }
-
             public Option(Text text, Text highlighted, float score, Boolean collateMatch) {
                 super(text, highlighted, score, collateMatch);
             }

server/src/main/java/org/elasticsearch/search/suggest/term/TermSuggestion.java

@@ -52,8 +52,6 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
 
     private SortBy sort;
 
-    public TermSuggestion() {}
-
     public TermSuggestion(String name, int size, SortBy sort) {
         super(name, size);
         this.sort = sort;
@@ -61,7 +59,6 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
 
     public TermSuggestion(StreamInput in) throws IOException {
         super(in);
-
         if (in.getVersion().onOrAfter(Version.V_7_0_0)) {
             sort = SortBy.readFromStream(in);
         }
@@ -80,7 +77,6 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
             }
             return FREQUENCY.compare(first, second);
         }
-
     }
 
     // Same behaviour as comparators in suggest module, but for SuggestedWord
@@ -105,7 +101,6 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
             // third criteria: term text
             return first.getText().compareTo(second.getText());
         }
-
     }
 
     @Override
@@ -154,11 +149,6 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
         return suggestion;
     }
 
-    @Override
-    protected Entry newEntry() {
-        return new Entry();
-    }
-
     @Override
     protected Entry newEntry(StreamInput in) throws IOException {
         return new Entry(in);
@@ -184,17 +174,12 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
             super(text, offset, length);
         }
 
-        public Entry() {}
+        private Entry() {}
 
         public Entry(StreamInput in) throws IOException {
             super(in);
         }
 
-        @Override
-        protected Option newOption() {
-            return new Option();
-        }
-
         @Override
         protected Option newOption(StreamInput in) throws IOException {
             return new Option(in);
@@ -236,10 +221,6 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
                 freq += ((Option) otherOption).freq;
             }
 
-            protected Option() {
-                super();
-            }
-
             public void setFreq(int freq) {
                 this.freq = freq;
             }
@@ -283,6 +264,5 @@ public class TermSuggestion extends Suggestion<TermSuggestion.Entry> {
                 return PARSER.apply(parser, null);
             }
         }
-
     }
 }

server/src/test/java/org/elasticsearch/search/SearchModuleTests.java

@@ -44,11 +44,11 @@ import org.elasticsearch.search.aggregations.bucket.significant.heuristics.Signi
 import org.elasticsearch.search.aggregations.bucket.significant.heuristics.SignificanceHeuristicParser;
 import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
 import org.elasticsearch.search.aggregations.pipeline.AbstractPipelineAggregationBuilder;
-import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 import org.elasticsearch.search.aggregations.pipeline.DerivativePipelineAggregationBuilder;
 import org.elasticsearch.search.aggregations.pipeline.DerivativePipelineAggregator;
 import org.elasticsearch.search.aggregations.pipeline.InternalDerivative;
 import org.elasticsearch.search.aggregations.pipeline.MovAvgModel;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 import org.elasticsearch.search.aggregations.pipeline.SimpleModel;
 import org.elasticsearch.search.aggregations.support.ValuesSource;
 import org.elasticsearch.search.aggregations.support.ValuesSourceAggregationBuilder;
@@ -579,11 +579,6 @@ public class SearchModuleTests extends ESTestCase {
             super(in);
         }
 
-        @Override
-        protected Entry newEntry() {
-            return null;
-        }
-
         @Override
         protected Entry newEntry(StreamInput in) throws IOException {
             return null;