Several `Comparable` classes do not override `equals()`, making `compareTo` inconsistent with `equals`

[shanjiang98]

Summary

Multiple classes in JTS implement Comparable with meaningful compareTo() implementations,
but do not override equals(). This means two objects considered equal by compareTo() (returns 0)
are not equal by equals() (identity comparison), violating the Comparable contract recommendation.

Affected classes

Class	compareTo compares by	File
DD	hi and lo double values	modules/core/src/.../math/DD.java
EdgeIntersection	segment index and distance	modules/core/src/.../geomgraph/EdgeIntersection.java
EdgeEnd	coordinates and direction	modules/core/src/.../geomgraph/EdgeEnd.java
LinearLocation	component/segment index + fraction	modules/core/src/.../linearref/LinearLocation.java
Corner	angle	modules/core/src/.../coverage/Corner.java
BoundablePair	distance	modules/core/src/.../index/strtree/BoundablePair.java
SweepLineEvent (sweepline)	x-value	modules/core/src/.../index/sweepline/SweepLineEvent.java
SweepLineEvent (geomgraph)	x-value	modules/core/src/.../geomgraph/index/SweepLineEvent.java
NodeSection	coordinates	modules/core/src/.../operation/relateng/NodeSection.java
OffsetCurveSection	location	modules/core/src/.../operation/buffer/OffsetCurveSection.java

Special case — DD: Has equals(DD y) (line 988) but this is NOT an override of
Object.equals(Object) — the parameter type is wrong. Standard Object.equals() (identity
comparison) is used in collections and by frameworks.

JDK contract reference

From Comparable Javadoc (JDK 21):

"It is strongly recommended, but not strictly required, that (x.compareTo(y)==0) == (x.equals(y)).
[...] Sorted sets (and sorted maps) without explicit comparators behave 'strangely' when they
are used with elements (or keys) whose natural ordering is inconsistent with equals."

Impact

Using these classes in TreeSet/TreeMap may cause unexpected behavior where elements considered
equal by the sorted collection's ordering are treated as distinct by equals()-based operations.

How this was found

Detected by an automated JDK conformance oracle (ComparableOracles.checkCompareToEqualsConsistency)
across 10 classes in the JTS codebase.