diff --git a/antlr4-maven-plugin/pom.xml b/antlr4-maven-plugin/pom.xml
index 901daeee8d..9d03e9e512 100644
--- a/antlr4-maven-plugin/pom.xml
+++ b/antlr4-maven-plugin/pom.xml
@@ -41,7 +41,7 @@
     <parent>
         <groupId>org.antlr</groupId>
         <artifactId>antlr4-master</artifactId>
-        <version>4.0.1-SNAPSHOT</version>
+        <version>4.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>antlr4-maven-plugin</artifactId>
@@ -76,7 +76,7 @@
         <dependency>
             <groupId>org.apache.maven</groupId>
             <artifactId>maven-plugin-api</artifactId>
-            <version>3.0.4</version>
+            <version>3.0.5</version>
             <scope>compile</scope>
         </dependency>
 
@@ -89,7 +89,7 @@
         <dependency>
             <groupId>org.codehaus.plexus</groupId>
             <artifactId>plexus-compiler-api</artifactId>
-            <version>2.0</version>
+            <version>2.2</version>
         </dependency>
 
         <!--
@@ -164,13 +164,13 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-site-plugin</artifactId>
-                <version>3.2</version>
+                <version>3.3</version>
             </plugin>
 
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-project-info-reports-plugin</artifactId>
-                <version>2.6</version>
+                <version>2.7</version>
                 <configuration>
                     <dependencyLocationsEnabled>false</dependencyLocationsEnabled>
                 </configuration>
diff --git a/build.xml b/build.xml
index 8e10363ff3..dbf697c560 100644
--- a/build.xml
+++ b/build.xml
@@ -20,7 +20,7 @@
     </target>
 
     <target name="build-init" depends="basic-init">
-        <property name="version" value="4.0.1-dev"/>
+        <property name="version" value="4.1-dev"/>
         <property name="build.sysclasspath" value="ignore"/>
         <property name="install.root.dir" value="${dist.dir}/antlr-${version}" />
         <property name="jar.file" value="${dist.dir}/antlr-${version}-complete.jar" />
diff --git a/pom.xml b/pom.xml
index d6a3f848fa..db531124c7 100644
--- a/pom.xml
+++ b/pom.xml
@@ -10,7 +10,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>org.antlr</groupId>
     <artifactId>antlr4-master</artifactId>
-    <version>4.0.1-SNAPSHOT</version>
+    <version>4.1-SNAPSHOT</version>
     <packaging>pom</packaging>
 
     <name>ANTLR 4</name>
@@ -132,7 +132,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.0</version>
+                <version>3.1</version>
                 <configuration>
                     <sourceDirectory>src</sourceDirectory>
                     <showWarnings>true</showWarnings>
@@ -181,7 +181,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
-                <version>2.12.4</version>
+                <version>2.15</version>
             </plugin>
 
             <plugin>
diff --git a/runtime/Java/pom.xml b/runtime/Java/pom.xml
index 2d43532c4c..ea30e8a406 100644
--- a/runtime/Java/pom.xml
+++ b/runtime/Java/pom.xml
@@ -6,7 +6,7 @@
     <parent>
         <groupId>org.antlr</groupId>
         <artifactId>antlr4-master</artifactId>
-        <version>4.0.1-SNAPSHOT</version>
+        <version>4.1-SNAPSHOT</version>
         <relativePath>../..</relativePath>
     </parent>
 
diff --git a/runtime/Java/src/org/antlr/v4/runtime/ANTLRErrorListener.java b/runtime/Java/src/org/antlr/v4/runtime/ANTLRErrorListener.java
index c38d9dc976..d78d446577 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/ANTLRErrorListener.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/ANTLRErrorListener.java
@@ -39,19 +39,19 @@
 
 import java.util.BitSet;
 
-/** How to emit recognition errors */
+/** How to emit recognition errors. */
 public interface ANTLRErrorListener {
-	/** Upon syntax error, notify any interested parties. This is not
-	 *  how to recover from errors or compute error messages. The
-	 *  parser ANTLRErrorStrategy specifies how to recover from syntax
-	 *  errors and how to compute error messages. This listener's job
-	 *  is simply to emit a computed message, though it has enough
-	 *  information to create its own message in many cases.
-	 *
-	 *  The RecognitionException is non-null for all syntax errors
-	 *  except when we discover mismatched token errors that we can
-	 *  recover from in-line, without returning from the surrounding
-	 *  rule (via the single token insertion and deletion mechanism).
+	/**
+	 * Upon syntax error, notify any interested parties. This is not how to
+	 * recover from errors or compute error messages. {@link ANTLRErrorStrategy}
+	 * specifies how to recover from syntax errors and how to compute error
+	 * messages. This listener's job is simply to emit a computed message,
+	 * though it has enough information to create its own message in many cases.
+	 * <p/>
+	 * The {@link RecognitionException} is non-null for all syntax errors except
+	 * when we discover mismatched token errors that we can recover from
+	 * in-line, without returning from the surrounding rule (via the single
+	 * token insertion and deletion mechanism).
 	 *
 	 * @param recognizer
      *        What parser got the error. From this
@@ -59,16 +59,15 @@ public interface ANTLRErrorListener {
 	 * 		  as the input stream.
 	 * @param offendingSymbol
 	 *        The offending token in the input token
-	 * 		  stream, unless recognizer is a lexer (then it's null) If
-	 * 		  no viable alternative error, e has token at which we
+	 * 		  stream, unless recognizer is a lexer (then it's null). If
+	 * 		  no viable alternative error, {@code e} has token at which we
 	 * 		  started production for the decision.
 	 * @param line
-	 * 		  At what line in input to the error occur? This always refers to
-	 * 		  stopTokenIndex
+	 * 		  The line number in the input where the error occurred.
 	 * @param charPositionInLine
-	 * 		  At what character position within that line did the error occur.
+	 * 		  The character position within that line where the error occurred.
 	 * @param msg
-	 * 		  The message to emit
+	 * 		  The message to emit.
 	 * @param e
 	 *        The exception generated by the parser that led to
 	 *        the reporting of an error. It is null in the case where
diff --git a/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java b/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java
index f66e482112..340a59e930 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/ANTLRFileStream.java
@@ -35,10 +35,9 @@
 import java.io.InputStreamReader;
 import java.util.Arrays;
 
-/** This is an ANTLRInputStream that is loaded from a file
- *  all at once when you construct the object.  This is a special case
- *  since we know the exact size of the object to load.  We can avoid lots
- *  of data copying.
+/**
+ * This is an {@link ANTLRInputStream} that is loaded from a file all at once
+ * when you construct the object.
  */
 public class ANTLRFileStream extends ANTLRInputStream {
 	protected String fileName;
diff --git a/runtime/Java/src/org/antlr/v4/runtime/ANTLRInputStream.java b/runtime/Java/src/org/antlr/v4/runtime/ANTLRInputStream.java
index fc57efa930..98db38dcef 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/ANTLRInputStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/ANTLRInputStream.java
@@ -37,10 +37,12 @@
 import java.io.Reader;
 import java.util.Arrays;
 
-/** Vacuum all input from a Reader/InputStream and then treat it like a char[] buffer.
- *  Can also pass in a string or char[] to use.
- *
- *  If you need encoding, pass in stream/reader with correct encoding.
+/**
+ * Vacuum all input from a {@link Reader}/{@link InputStream} and then treat it
+ * like a {@code char[]} buffer. Can also pass in a {@link String} or
+ * {@code char[]} to use.
+ * <p/>
+ * If you need encoding, pass in stream/reader with correct encoding.
  */
 public class ANTLRInputStream implements CharStream {
     public static final int READ_BUFFER_SIZE = 1024;
diff --git a/runtime/Java/src/org/antlr/v4/runtime/BufferedTokenStream.java b/runtime/Java/src/org/antlr/v4/runtime/BufferedTokenStream.java
index 83420a864b..f0848f9145 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/BufferedTokenStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/BufferedTokenStream.java
@@ -38,36 +38,38 @@
 import java.util.List;
 import java.util.Set;
 
-/** Buffer all input tokens but do on-demand fetching of new tokens from
- *  lexer. Useful when the parser or lexer has to set context/mode info before
- *  proper lexing of future tokens. The ST template parser needs this,
- *  for example, because it has to constantly flip back and forth between
- *  inside/output templates. E.g., <names:{hi, <it>}> has to parse names
- *  as part of an expression but "hi, <it>" as a nested template.
- *
- *  You can't use this stream if you pass whitespace or other off-channel
- *  tokens to the parser. The stream can't ignore off-channel tokens.
- *  (UnbufferedTokenStream is the same way.)  Use CommonTokenStream.
- *
- *  This is not a subclass of UnbufferedTokenStream because I don't want
- *  to confuse small moving window of tokens it uses for the full buffer.
+/**
+ * Buffer all input tokens but do on-demand fetching of new tokens from lexer.
+ * Useful when the parser or lexer has to set context/mode info before proper
+ * lexing of future tokens. The ST template parser needs this, for example,
+ * because it has to constantly flip back and forth between inside/output
+ * templates. E.g., {@code <names:{hi, <it>}>} has to parse names as part of an
+ * expression but {@code "hi, <it>"} as a nested template.
+ * <p/>
+ * You can't use this stream if you pass whitespace or other off-channel tokens
+ * to the parser. The stream can't ignore off-channel tokens.
+ * ({@link UnbufferedTokenStream} is the same way.) Use
+ * {@link CommonTokenStream}.
  */
 public class BufferedTokenStream implements TokenStream {
 	@NotNull
     protected TokenSource tokenSource;
 
-    /** Record every single token pulled from the source so we can reproduce
-     *  chunks of it later.  The buffer in LookaheadStream overlaps sometimes
-     *  as its moving window moves through the input.  This list captures
-     *  everything so we can access complete input text.
-     */
+	/**
+	 * Record every single token pulled from the source so we can reproduce
+	 * chunks of it later. This list captures everything so we can access
+	 * complete input text.
+	 */
     protected List<Token> tokens = new ArrayList<Token>(100);
 
-    /** The index into the tokens list of the current token (next token
-     *  to consume).  tokens[p] should be LT(1).  p=-1 indicates need
-     *  to initialize with first token.  The ctor doesn't get a token.
-     *  First call to LT(1) or whatever gets the first token and sets p=0;
-     */
+	/**
+	 * The index into {@link #tokens} of the current token (next token to
+	 * consume). {@link #tokens}{@code [}{@link #p}{@code ]} should be
+	 * {@link #LT LT(1)}. {@link #p}{@code =-1} indicates need to initialize
+	 * with first token. The constructor doesn't get a token. First call to
+	 * {@link #LT LT(1)} or whatever gets the first token and sets
+	 * {@link #p}{@code =0;}.
+	 */
     protected int p = -1;
 
 	/**
@@ -92,8 +94,6 @@ public BufferedTokenStream(TokenSource tokenSource) {
 	@Override
 	public int index() { return p; }
 
-//	public int range() { return range; }
-
     @Override
     public int mark() {
 		return 0;
diff --git a/runtime/Java/src/org/antlr/v4/runtime/atn/ATNConfigSet.java b/runtime/Java/src/org/antlr/v4/runtime/atn/ATNConfigSet.java
index ba638f671d..423c1e9679 100755
--- a/runtime/Java/src/org/antlr/v4/runtime/atn/ATNConfigSet.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/atn/ATNConfigSet.java
@@ -44,201 +44,18 @@
 import java.util.List;
 import java.util.Set;
 
-/** Specialized OrderedHashSet that can track info about the set.
- *  Might be able to optimize later w/o affecting code that uses this set.
-
- histogram of lexer DFA configset size:
-
- 206 30  <- 206 sets with size 30
-  47 1
-  17 31
-  12 2
-  10 3
-   7 32
-   4 4
-   3 35
-   2 9
-   2 6
-   2 5
-   2 34
-   1 7
-   1 33
-   1 29
-   1 12
-   1 119 <- max size
-
- 322 set size for SLL parser java.* in DFA states:
-
- 888 1
- 411 54
- 365 88
- 304 56
- 206 80
- 182 16
- 167 86
- 166 78
- 158 84
- 131 2
- 121 20
- 120 8
- 119 112
-  82 10
-  73 6
-  53 174
-  47 90
-  45 4
-  39 12
-  38 122
- 37 89
- 37 62
- 34 3
- 34 18
- 32 81
- 31 87
- 28 45
- 27 144
- 25 41
- 24 132
- 22 91
- 22 7
- 21 82
- 21 28
- 21 27
- 17 9
- 16 29
- 16 155
- 15 51
- 15 118
- 14 146
- 14 114
- 13 5
- 13 38
- 12 48
- 11 64
- 11 50
- 11 22
- 11 134
- 11 131
- 10 79
- 10 76
- 10 59
- 10 58
- 10 55
- 10 39
- 10 116
-  9 74
-  9 47
-  9 310
-   ...
-
- javalr, java.* configs with # preds histogram:
-
- 4569 0
-   57 1
-   27 27
-    5 76
-    4 28
-    3 72
-    3 38
-    3 30
-    2 6
-    2 32
-    1 9
-    1 2
-
- javalr, java.* all atnconfigsets; max size = 322, num sets = 269088
-
- 114186 1    <-- optimize
- 35712 6
- 28081 78
- 15252 54
- 14171 56
- 13159 12
- 11810 88
- 6873 86
- 6158 80
- 5169 4
- 3773 118
- 2350 16
- 1002 112
-  915 28
-  898 44
-  734 2
-  632 62
-  575 8
-  566 59
-  474 20
-  388 84
-  343 48
-  333 55
-  328 47
-  311 41
-  306 38
-  277 81
-  263 79
-  255 66
-  245 90
-  245 87
-  234 50
-  224 10
-  220 60
-  194 64
-  186 32
-  184 82
-  150 18
-  125 7
-  121 132
-  116 30
-  103 51
-   95 114
-   84 36
-   82 40
-   78 22
-   77 89
-   55 9
-   53 174
-   48 152
-   44 67
-   44 5
-   42 115
-   41 58
-   38 122
-   37 134
-   34 13
-   34 116
-   29 45
-   29 3
-   29 24
-   27 144
-   26 146
-   25 91
-   24 113
-   20 27
-   ...
-
- number with 1-9 elements:
-
- 114186 1
- 35712 6
- 5169 4
-  734 2
-  575 8
-  125 7
-   55 9
-   44 5
-   29 3
-
- Can cover 60% of sizes with size up to 6
- Can cover 44% of sizes with size up to 4
- Can cover 42% of sizes with size up to 1
+/**
+ * Specialized {@link Set}{@code <}{@link ATNConfig}{@code >} that can track
+ * info about the set, with support for combining similar configurations using a
+ * graph-structured stack.
  */
 public class ATNConfigSet implements Set<ATNConfig> {
-	/*
-	The reason that we need this is because we don't want the hash map to use
-	the standard hash code and equals. We need all configurations with the same
-	(s,i,_,semctx) to be equal. Unfortunately, this key effectively doubles
-	the number of objects associated with ATNConfigs. The other solution is to
-	use a hash table that lets us specify the equals/hashcode operation.
+	/**
+	 * The reason that we need this is because we don't want the hash map to use
+	 * the standard hash code and equals. We need all configurations with the same
+	 * {@code (s,i,_,semctx)} to be equal. Unfortunately, this key effectively doubles
+	 * the number of objects associated with ATNConfigs. The other solution is to
+	 * use a hash table that lets us specify the equals/hashcode operation.
 	 */
 	public static class ConfigHashSet extends AbstractConfigHashSet {
 		public ConfigHashSet() {
@@ -279,8 +96,9 @@ public boolean equals(ATNConfig a, ATNConfig b) {
  	 */
 	protected boolean readonly = false;
 
-	/** All configs but hashed by (s, i, _, pi) not incl context.  Wiped out
-	 *  when we go readonly as this set becomes a DFA state.
+	/**
+	 * All configs but hashed by (s, i, _, pi) not including context. Wiped out
+	 * when we go readonly as this set becomes a DFA state.
 	 */
 	public AbstractConfigHashSet configLookup;
 
diff --git a/runtime/Java/src/org/antlr/v4/runtime/atn/ArrayPredictionContext.java b/runtime/Java/src/org/antlr/v4/runtime/atn/ArrayPredictionContext.java
index 5540622fed..68fbbc0be1 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/atn/ArrayPredictionContext.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/atn/ArrayPredictionContext.java
@@ -59,8 +59,9 @@ public ArrayPredictionContext(PredictionContext[] parents, int[] returnStates) {
 
 	@Override
 	public boolean isEmpty() {
-		return size()==1 &&
-			   returnStates[0]==EMPTY_RETURN_STATE;
+		// since EMPTY_RETURN_STATE can only appear in the last position, we
+		// don't need to verify that size==1
+		return returnStates[0]==EMPTY_RETURN_STATE;
 	}
 
 	@Override
diff --git a/runtime/Java/src/org/antlr/v4/runtime/atn/PredictionContext.java b/runtime/Java/src/org/antlr/v4/runtime/atn/PredictionContext.java
index 1ddcf5d2da..83ad70a354 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/atn/PredictionContext.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/atn/PredictionContext.java
@@ -234,7 +234,6 @@ public static PredictionContext merge(
 	 * @param rootIsWildcard {@code true} if this is a local-context merge,
 	 * otherwise false to indicate a full-context merge
 	 * @param mergeCache
-	 * @return
 	 */
 	public static PredictionContext mergeSingletons(
 		SingletonPredictionContext a,
diff --git a/runtime/Java/src/org/antlr/v4/runtime/dfa/DFA.java b/runtime/Java/src/org/antlr/v4/runtime/dfa/DFA.java
index 694783a32f..091a071618 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/dfa/DFA.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/dfa/DFA.java
@@ -29,11 +29,7 @@
  */
 package org.antlr.v4.runtime.dfa;
 
-import org.antlr.v4.runtime.TokenStream;
-import org.antlr.v4.runtime.atn.ATNState;
 import org.antlr.v4.runtime.atn.DecisionState;
-import org.antlr.v4.runtime.atn.ParserATNSimulator;
-import org.antlr.v4.runtime.atn.Transition;
 import org.antlr.v4.runtime.misc.NotNull;
 import org.antlr.v4.runtime.misc.Nullable;
 
@@ -41,7 +37,6 @@
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -61,11 +56,6 @@ public class DFA {
 	@NotNull
 	public final DecisionState atnStartState;
 
-	/** Set of configs for a DFA state with at least one conflict? Mainly used as "return value"
-	 *  from {@link ParserATNSimulator#predictATN} for retry.
-	 */
-//	public OrderedHashSet<ATNConfig> conflictSet;
-
 	public DFA(@NotNull DecisionState atnStartState) {
 		this(atnStartState, 0);
 	}
diff --git a/runtime/Java/src/org/antlr/v4/runtime/dfa/DFAState.java b/runtime/Java/src/org/antlr/v4/runtime/dfa/DFAState.java
index 4cf7579d14..49005a6a61 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/dfa/DFAState.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/dfa/DFAState.java
@@ -94,7 +94,7 @@ public class DFAState {
 	/**
 	 * Indicates that this state was created during SLL prediction that
 	 * discovered a conflict between the configurations in the state. Future
-	 * {@link ParserATNSimulator#execDFA} invocations immediately jumped doing
+	 * {@link ParserATNSimulator#execATN} invocations immediately jumped doing
 	 * full context prediction if this field is true.
 	 */
 	public boolean requiresFullContext;
diff --git a/tool/pom.xml b/tool/pom.xml
index 7fe54993ea..bbda5f8adf 100644
--- a/tool/pom.xml
+++ b/tool/pom.xml
@@ -6,7 +6,7 @@
     <parent>
         <groupId>org.antlr</groupId>
         <artifactId>antlr4-master</artifactId>
-        <version>4.0.1-SNAPSHOT</version>
+        <version>4.1-SNAPSHOT</version>
     </parent>
 
     <artifactId>antlr4</artifactId>
@@ -49,7 +49,7 @@
                     <plugin>
                         <groupId>org.apache.maven.plugins</groupId>
                         <artifactId>maven-shade-plugin</artifactId>
-                        <version>2.0</version>
+                        <version>2.1</version>
                         <inherited>false</inherited>
                         <executions>
                             <execution>
diff --git a/tool/src/org/antlr/v4/codegen/JavaTarget.java b/tool/src/org/antlr/v4/codegen/JavaTarget.java
index 25203819f6..5d112c8d98 100644
--- a/tool/src/org/antlr/v4/codegen/JavaTarget.java
+++ b/tool/src/org/antlr/v4/codegen/JavaTarget.java
@@ -77,6 +77,18 @@ protected void addBadWords() {
 		badWords.add("parserRule");
 	}
 
+	/**
+	 * {@inheritDoc}
+	 * <p/>
+	 * For Java, this is the translation {@code 'a\n"'} &rarr; {@code "a\n\""}.
+	 * Expect single quotes around the incoming literal. Just flip the quotes
+	 * and replace double quotes with {@code \"}.
+	 * <p/>
+	 * Note that we have decided to allow people to use '\"' without penalty, so
+	 * we must build the target string in a loop as {@link String#replace}
+	 * cannot handle both {@code \"} and {@code "} without a lot of messing
+	 * around.
+	 */
 	@Override
 	public String getTargetStringLiteralFromANTLRStringLiteral(
 		CodeGenerator generator,
diff --git a/tool/src/org/antlr/v4/codegen/Target.java b/tool/src/org/antlr/v4/codegen/Target.java
index ed862f2e89..b65aef07fe 100644
--- a/tool/src/org/antlr/v4/codegen/Target.java
+++ b/tool/src/org/antlr/v4/codegen/Target.java
@@ -191,14 +191,7 @@ public String getTargetStringLiteralFromString(String s) {
 
 	/**
 	 * Convert from an ANTLR string literal found in a grammar file to an
-	 * equivalent string literal in the target language. For Java, this is the
-	 * translation {@code 'a\n"'} &rarr; {@code "a\n\""}. Expect single quotes
-	 * around the incoming literal. Just flip the quotes and replace double
-	 * quotes with {@code \"}.
-	 * <p/>
-	 * Note that we have decided to allow people to use '\"' without penalty, so
-	 * we must build the target string in a loop as {@link Utils#replace} cannot
-	 * handle both {@code \"} and {@code "} without a lot of messing around.
+	 * equivalent string literal in the target language.
 	 */
 	public abstract String getTargetStringLiteralFromANTLRStringLiteral(
 		CodeGenerator generator,