Type cache in API extraction for smaller cache size and faster I/O

manually implement Modifiers, use byte-size bit field

interface/src/main/java/xsbti/api/Modifiers.java

@@ -0,0 +1,69 @@
+package xsbti.api;
+
+public final class Modifiers implements java.io.Serializable
+{
+	private static final int AbstractBit = 0;
+	private static final int OverrideBit = 1;
+	private static final int FinalBit = 2;
+	private static final int SealedBit = 3;
+	private static final int ImplicitBit = 4;
+	private static final int LazyBit = 5;
+
+	private static final int flag(boolean set, int bit)
+	{
+		return set ? (1 << bit) : 0;
+	}
+
+	public Modifiers(boolean isAbstract, boolean isOverride, boolean isFinal, boolean isSealed, boolean isImplicit, boolean isLazy)
+	{
+		this.flags = (byte)(
+			flag(isAbstract, AbstractBit) |
+			flag(isOverride, OverrideBit) |
+			flag(isFinal, FinalBit) |
+			flag(isSealed, SealedBit) |
+			flag(isImplicit, ImplicitBit) |
+			flag(isLazy, LazyBit)
+		);
+	}
+
+	private final byte flags;
+
+	private final boolean flag(int bit)
+	{
+		return (flags & (1 << bit)) != 0;
+	}
+
+	public final byte raw()
+	{
+		return flags;
+	}
+
+	public final boolean isAbstract()
+	{
+		return flag(AbstractBit);
+	}
+	public final boolean isOverride()
+	{
+		return flag(OverrideBit);
+	}
+	public final boolean isFinal()
+	{
+		return flag(FinalBit);
+	}
+	public final boolean isSealed()
+	{
+		return flag(SealedBit);
+	}
+	public final boolean isImplicit()
+	{
+		return flag(ImplicitBit);
+	}
+	public final boolean isLazy()
+	{
+		return flag(LazyBit);
+	}
+	public String toString()
+	{
+		return "Modifiers(" + "isAbstract: " + isAbstract() + ", " + "isOverride: " + isOverride() + ", " + "isFinal: " + isFinal() + ", " + "isSealed: " + isSealed() + ", " + "isImplicit: " + isImplicit() + ", " + "isLazy: " + isLazy()+ ")";
+	}
+}