refactor(java): replace Guava's string utility methods with own implementation

java/fury-core/src/main/java/org/apache/fury/util/StringUtils.java

@@ -19,16 +19,22 @@
 
 package org.apache.fury.util;
 
-import com.google.common.io.BaseEncoding;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Random;
 
 public class StringUtils {
+  private static final char[] BASE16_CHARS2 = {
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
+  };
 
   /** Converts a bytes array into a hexadecimal string. */
   public static String encodeHexString(final byte[] data) {
-    return BaseEncoding.base16().lowerCase().encode(data);
+    StringBuilder result = new StringBuilder(data.length * 2);
+    for (byte b : data) {
+      result.append(BASE16_CHARS2[(b >>> 4) & 0xF]).append(BASE16_CHARS2[b & 0xF]);
+    }
+    return result.toString();
   }
 
   /** Format a string template by replacing all `${xxx}` into provided values. */
@@ -192,4 +198,55 @@ public static String repeat(String str, int numRepeat) {
     }
     return builder.toString();
   }
+
+  // example: "variable_name" -> "variableName"
+  public static String lowerUnderscoreToLowerCamelCase(String lowerUnderscore) {
+    StringBuilder builder = new StringBuilder();
+    int length = lowerUnderscore.length();
+
+    int index;
+    int fromIndex = 0;
+    while ((index = lowerUnderscore.indexOf('_', fromIndex)) != -1) {
+      builder.append(lowerUnderscore, fromIndex, index);
+
+      if (length >= index + 1) {
+        char symbol = lowerUnderscore.charAt(index + 1);
+        if (symbol >= 'a' && symbol <= 'z') {
+          builder.append(Character.toUpperCase(symbol));
+          fromIndex = index + 2;
+          continue;
+        }
+      }
+
+      fromIndex = index + 1;
+    }
+
+    if (fromIndex < length) {
+      builder.append(lowerUnderscore, fromIndex, length);
+    }
+
+    return builder.toString();
+  }
+
+  // example: "variableName" -> "variable_name"
+  public static String lowerCamelToLowerUnderscore(String lowerCamel) {
+    StringBuilder builder = new StringBuilder();
+    int length = lowerCamel.length();
+
+    int fromIndex = 0;
+
+    for (int i = 0; i < length; i++) {
+      char symbol = lowerCamel.charAt(i);
+      if (symbol >= 'A' && symbol <= 'Z') {
+        builder.append(lowerCamel, fromIndex, i).append('_').append(Character.toLowerCase(symbol));
+        fromIndex = i + 1;
+      }
+    }
+
+    if (fromIndex < length) {
+      builder.append(lowerCamel, fromIndex, length);
+    }
+
+    return builder.toString();
+  }
 }

java/fury-core/src/test/java/org/apache/fury/util/StringUtilsTest.java

@@ -62,4 +62,29 @@ public void testIsBlank() {
     assertTrue(StringUtils.isBlank("   "));
     assertTrue(StringUtils.isBlank(null));
   }
+
+  @Test
+  public void testLowerUnderscoreToLowerCamelCase() {
+    assertEquals(StringUtils.lowerUnderscoreToLowerCamelCase("some_variable"), "someVariable");
+    assertEquals(
+        StringUtils.lowerUnderscoreToLowerCamelCase("some_long_variable"), "someLongVariable");
+    assertEquals(
+        StringUtils.lowerUnderscoreToLowerCamelCase("some_123variable"), "some123variable");
+    assertEquals(
+        StringUtils.lowerUnderscoreToLowerCamelCase("some_variable123"), "someVariable123");
+    assertEquals(
+        StringUtils.lowerUnderscoreToLowerCamelCase("some_variable123"), "someVariable123");
+    assertEquals(
+        StringUtils.lowerUnderscoreToLowerCamelCase("some_123_variable"), "some123Variable");
+    assertEquals(
+        StringUtils.lowerUnderscoreToLowerCamelCase("some_variable_123"), "someVariable123");
+  }
+
+  @Test
+  public void testLowerCamelToLowerUnderscore() {
+    assertEquals(StringUtils.lowerCamelToLowerUnderscore("someVariable"), "some_variable");
+    assertEquals(StringUtils.lowerCamelToLowerUnderscore("someLongVariable"), "some_long_variable");
+    assertEquals(StringUtils.lowerCamelToLowerUnderscore("some123variable"), "some123variable");
+    assertEquals(StringUtils.lowerCamelToLowerUnderscore("someVariable123"), "some_variable123");
+  }
 }

java/fury-format/src/main/java/org/apache/fury/format/encoder/RowEncoderBuilder.java

@@ -22,7 +22,6 @@
 import static org.apache.fury.type.TypeUtils.CLASS_TYPE;
 import static org.apache.fury.type.TypeUtils.getRawType;
 
-import com.google.common.base.CaseFormat;
 import java.lang.reflect.Modifier;
 import java.util.SortedMap;
 import org.apache.arrow.vector.types.pojo.Field;
@@ -218,7 +217,7 @@ public Expression buildDecodeExpression() {
   }
 
   private Descriptor getDescriptorByFieldName(String fieldName) {
-    String name = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, fieldName);
+    String name = StringUtils.lowerUnderscoreToLowerCamelCase(fieldName);
     return descriptorsMap.get(name);
   }
 

java/fury-format/src/main/java/org/apache/fury/format/type/TypeInference.java

@@ -22,7 +22,6 @@
 import static org.apache.fury.format.type.DataTypes.field;
 import static org.apache.fury.type.TypeUtils.getRawType;
 
-import com.google.common.base.CaseFormat;
 import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -43,6 +42,7 @@
 import org.apache.fury.type.TypeUtils;
 import org.apache.fury.util.DecimalUtils;
 import org.apache.fury.util.Preconditions;
+import org.apache.fury.util.StringUtils;
 
 /** Arrow related type inference. */
 @SuppressWarnings("UnstableApiUsage")
@@ -226,9 +226,7 @@ private static Field inferField(
                   descriptor -> {
                     LinkedHashSet<Class<?>> newSeenTypeSet = new LinkedHashSet<>(seenTypeSet);
                     newSeenTypeSet.add(rawType);
-                    String n =
-                        CaseFormat.LOWER_CAMEL.to(
-                            CaseFormat.LOWER_UNDERSCORE, descriptor.getName());
+                    String n = StringUtils.lowerCamelToLowerUnderscore(descriptor.getName());
                     return inferField(n, descriptor.getTypeRef(), newSeenTypeSet);
                   })
               .collect(Collectors.toList());